I am having similar issues.
After using Evernote for years, logging into the web interface is now knocking my iPhone app off of the 'authorized access' list.
It does this without prompting me to remove my iphone (which I would never do)
Then, when I try to re-sync my iphone, Evernote forces me to unsync a device and tells me I can only do it a limited amount of times.
This new restriction is horrible and also seems like it has a bug.
Web access was never considered a "sync" device in the past, now it is. Plus, it gives you no warning that it will be removing a device.
It only warns you when you try to put the device back.
If this isn't corrected quickly, it may be time to move on to another app.