Same Here! It's quite frustrating, though I'm glad I'm not the only one that has the problem since maybe they'll do something about it.
editing any note at all gives me the error about syncing.
I've gone through everything on this list: https://help.evernote.com/hc/en-us/articles/hc/articles/208313378 (no help)
Can't ticket support since I'm a poor pleb, would be a shame to have to switch to some other service with so much data organized here already.
Please get on this. No way in heck I'd consider paying for this product until this is resolved