Here's Pleexy's article referencing this issue: https://help.pleexy.com/en/articles/7982892-why-aren-t-your-tasks-being-completed-in-evernote
Overall, third-party integrations using Evernote's SDK are NOT working properly.
I have tested IFTTT, Zapier, and Pleexy, and all of them don't update the content in the note. Although the integration indicates that the note has been updated and I can see the changes in the note preview, the actual changes are not reflected in the note itself.
An example of IFTTT:
I have an applet that appends a to-do in Evernote when new tasks are created in Todoist.
ITTF shows that the item was added.
The todo appears in the note preview, but not in the actual note. Even reloading the page doesn't help.
I wrote a small Node.js script using Evernote's official SDK that also doesn't work. Although I see the changes when I get the note again via SDK and I see the applied changes in the Evernote preview, the changes do not show up in the actual Evernote content.
Script: https://pastebin.com/Hqh8WyTR
The preview shows the updated content, but the note isn’t being updated.