i've had this issue since sometime last year. i've just been restarting the app to get it to work again. relieved i'm not missing notes. am a beta tester but didn't notice this problem before, and sounds like that doesn't matter from this thread. but at this point, does have me wondering if my annual premium subscription is worth the hassle of having to restart whenever I want to add to any of my previous notes. i've loved evernote for a long time, so I would be really sad to leave.
I'm on a mac big sur, copied my evernote version below. hope that this will be fixed soon, otherwise i guess i'll revert to apple notes.