PinkElephant

Or solve the problem at the root and merge the two accounts into one:
https://help.evernote.com/hc/en-us/articles/209004867

This page shows the latest software for the S1500 scanner:
https://www.fujitsu.com/global/support/products/computing/peripheral/scanners/scansnap/software/s1500.html
You find a note at the bottom of the table that the auto-update does not work for this scanner !
 

 

You can't sync that version: Wrong
Hold down the ctrl key (I think so, maybe it is alt/opt) before clicking on the Help menu. There will be a new option "troubleshooting", inside of it the first 2 options are "Reload" and "Force Reload". Imagine what their purpose may be ... ?
You are probably in need of some troubleshooting as well. It looks as if your local Windows database took a hit somewhere down the road. You can fix it following this procedure:
Go to File > Sign Out [name] from the menu bar. Select the "Remove my Evernote data from this device" option, then click Sign out. Restart your computer. Sign back in to Evernote This should solve the other issues you described.

I think you may need a complete uninstall, not just the usual ***** Windows offers. It leaves old files on the drive.
Get an uninstaller (Revo Uninstaller was mentioned in the forum, I am on a Mac), install it and run it to get rid of every piece of software and data from the EN installation.
Then restart the PC, and install a fresh copy of EN from the Evernote.com website.

So the note is still there, it is on the web as well, but it is only the title ?
Do you have a desktop client available ? Are you on a subscription ?
Then it is possible to recover the note through note history. Open the note in the desktop client, click on 3 dots top right, select Note Information, and below the fields with note informations you see a text link to go back to prior versions. You can set the note back, or restore to an older version as a copy.
If you are not on a subscription, you can decide: If you subscribe for a month, note history becomes accessible. It runs on Free accounts in the background as well, but to access it, you need to be a subscriber. So it is basically the question if the lost content is worth a month of Personal subscription.

No - and the usual way of learning it is available will be by reading about it in the release notes.
Currently the only way for all „other“ calendars is to create a Google calendar, sync to it and then sync the Google calendar to your EN account.

Any further filter active ? Filters by default work with a logical AND - 2 filters will exclude all notes with only one of the two items occurring.
Else your local database may be corrupted. You can force a reload from the server by this procedure:
Go to File > Sign Out [name] from the menu bar. Select the "Remove my Evernote data from this device" option, then click Sign out. Restart your computer. Sign back in to Evernote

You can install the legacy client side by side on desktops.
https://help.evernote.com/hc/en-us/articles/360052560314-Install-an-older-version-of-Evernote I agree that for tag management, the new overview is falling short from what existed before. To send your claim to EN, use the feedback function build into the clients.

@Tarra32 Nothing easier than that (OK, little exaggeration, it is quite hidden):
When the card was created, click/tap on the header, where it says „Contact“. A pencil appears, above in the desktop app, below on mobile, Click/tap it.
A window opens, with all the extracted information in fields. They are fully editable. You can even add more information that was not extracted. Click Save, and the card is changed.
It allows you to add a new picture to an existing contact as well.

The simple answer is: You can’t search for an exact match of a whole sentence. The reason behind it is how the search index is build. EN explains it in a document about the advanced search grammar, but in short they convert the text in a document into a list of words. The sentence is not searchable, because it does not exist in the search index.
But you can use the key words from your sentence (skipping words like And, The, It and so on), and it should find the sentence.
Here is the relevant passage from the grammar description ( https://dev.evernote.com/doc/articles/search_grammar.php)  :
The behavior of a quoted search should behave as if the following operations were performed on both the search query and the target note:
All XML markup is removed from the document, leaving only the visible text as a string The string is converted to a list of words which are separated by one or more whitespace and/or punctuation characters. The case of each word in the list is normalized The list of words in the query must match with the same sequence of words in the converted Note For example, if a user searches for the phrase "Spatula! City! For Bargains..." against this ENML document: 
The algorithm should convert the search phrase into a normalized list of words:
[ "spatula", "city", "for", "bargains" ]
And the document into: 
[ "come", "down", "to", "spatula", "city", "for", "bargains", "on", "spatulas" ]
The search should match, since words from the target phrase are found in the list of words extracted from the document. (The same result could be implemented without literally converting each note into a list of words, but this gives the intended behavior that we see from major search engines like Google and MS.) 
 

Then try in the notification to tap on Accept or Continue or whatever (I don’t get these notifications).
It worked in the past when you accepted the popups offer first, and broke it off on the following page. It usually did not return.

No, it opens in the integrated browser first.

This is a weird one. I would contact support, from the same device, providing an activity log.
Support is in App settings, tab support.
In this case I think the Sketch got lost, whyever. To put it on a more stable footing in the future, open the note for the Sketch and insert the Sketch. Write something into the sketch.
Now close the sketch and wait it to show in the note. Then close the note once to save it and get it synced with the server. After this open it again and open the Sketch for note taking.
This is just a collection of ideas to make syncing more secure, as a workaround.
For iOS there is an alternative, the Penultimate app. It is free, iOS only and made for handwritten notes. It will sync with a notebook in your account.

It will take a long time ….
At least it takes a long time on iOS.
Best way is to switch off the lockscreen, put the device on charger and make EN the active app during the night. It will download when you don’t need it.
My 8k of notes took 3 nights to transfer to my iPad Pro, with a lot of memory and on fast WiFi.

EN still requires Android 10 or up as OS. They said they will look at earlier Android versions, but watching the problems with the newer ones I doubt it will happen.
As a consequence the PlayStore offers EN legacy as compatible version.

The relevant folders seem to be %AppData%\Evernote and %LocalAppData%\Programs\Evernote.
Can't try, I am on a Mac.

The only version that will not auto-update is the legacy client 7.14 posted by @gazumped . Installing 7.12 will not do, because these older versions are not set to never update - legacy has this eternity switch enabled. Since Windows never reached the 7.-release numbers, I assume you run EN on a Mac.
You can install and use legacy alone or side by side with v10. However, there is no guarantee for how long it will stay available. If you have any mission critical workflows, you should think about migrating NOW while it still works.
For Mac users DEVONthink is a solid alternative with local storage.

Maybe yes - and this proves what ?
v10 is a new software, that does things differently from the old, native clients. Some things will be added with releases, as EN did in the past year, others will be gone for good.
You can issue a support ticket if you miss something you direly need, or just loved and want back. 
Personally I plan for what functions I get with todays releases, and am happy with every additional function I get over time. The scale is by no means only tipping to functions that were there and are now MIA - there are plenty of other functions that never have been there, until v10 was launched and since improved. You can use legacy clients for desktop and Android, as long as they work, if you want to.
In the long run my opinion is a user needs to make his peace with v10, or draw the consequences and migrate to another service.

Mobile app, settings, account:
Shows used and total upload, plus days until the next reset. Similar on the account view in the web.

Probably there is corrupted content at the local database. You can try to correct is by this procedure:
Go to File > Sign Out [name] from the menu bar. Select the "Remove my Evernote data from this device" option, then click Sign out. Restart your computer. Sign back in to Evernote

Good move ! A password manager will not only help you to store your passwords - it will help you create new, good ones as well, can handle 2FA, will warn you against reusing passwords, will check in internet databases if you use known passwords (which makes breaking them much easier, by the use of rainbow tables), etc.
Since we all rely on many online accounts these days, keeping them safe should be a top priority.

Maybe something is broken in your local EN database. Sometimes it helps just to log out.
If not you can try this to revive it:
Go to the Evernote menu, Preferences, and uncheck „Keep data when leaving“ Log out of EN (File menu), quit EN (cmd-q). When asked confirm "Remove Data from This Device". If you want to be very sure, restart the Mac Open EN, log back in, wait for it to run an initial sync. 

Just a word of caution: We are talking here about swapping devices / clients. But this is a Free account, entitled to only 2 devices at any time, and there are only 2 unsyncs of devices/clients allowed per month. This is not really a lot.
In any case I would plot the strategy first before starting to try in the real world. Worst case is a lock out of all working devices.
It would be much easier to subscribe for a month, which will lift the device limit.
P.S. About how one can see content if the complete file is on the EN server: EN stores enough information on mobile devices to show the notes, and make them searchable. This is only a fraction of the whole database, just some metadata, small thumbnail pictures and enough text to show the notes overview. When a note is then opened, the content is loaded from the server.

When you open web clipper, go to settings.
On top of the settings page is an icon and name for your account, below it is a button to log out of it.
Log out, log back in on the account you want to use.

Rebuild the local database on Windows:
Go to File > Sign Out [name] from the menu bar. Select the "Remove my Evernote data from this device" option, then click Sign out. Restart your computer. Sign back in to Evernote   On a Mac, it is similar, just the menu items are named a bit differently.