I have the same, new issue on Mojave - could SOMEONE please answer????
After panic-mode, found a topic of sudden problems reported back in May. I followed the advice of Nick L. I gave my Admin password and clicked the sync circles. I felt dread when when I saw 2011 items reappear, but…in 20 minutes, this old lady felt as if magic had worked and life is back with all 19,000+ notes are back in place. No thanks to Safari's upgrade or whatever, but life goes on happily. Thank you Nick!