comment symbol in some cells shows "add comment" when right clicked

Comment symbol in some cells shows nothing when moused over, and “add comment” when right clicked.
Other comments with comment symbol work normally: when moused over - show the comment, and when right clicked - provide (edit/delete/show) comment options.

How do I recover comments showing comment symbols, but not showing comments themselves?

I’ve only tried shutting down calc and restarting. Next I’ll try restarting all of LibreOffice.

I’m on 5.3.4.2
Thanks,