I have the same problem, and actually noticed it since WP 5.6.x update.
My workaround has been to create a new / copy an existing Pop-up.
The latter seems to also enable one edit and save as it is duplicating a good row.
Thereafter, it does not allow changes.
I have used Inspector and Query monitor, even disabled cloudflare and all other plugin’s and the issue persists.
It seems, somewhere in the stack there is the following “Warning” on loading any newly saved Popups, that did not happen in the originals I have built I think around WP 5.3:
[DOM] Found 2 elements with non-unique id #active_date_check: (More info: https://goo.gl/9p2vKq)
<input id=?”active_date_check” type=?”checkbox” class=?”active_date_check ays_toggle_checkbox” name=?”active_date_check”>?
<input id=?”active_date_check” type=?”checkbox” class=?”active_date_check ays_toggle_checkbox” checked>?
I regularly check developer console for warnings and errors and this has been a recent occurence.
I have even cleared all browser cache and cookies and used incognito in new sessions to make sure it is not some rouge local browser cookie / cache.
I hope you can identify how / why this happens as to me it indicates the DB entry is getting corrupt and therefore unable to update, even though it says saved – I used Query Monitor to check and oddly see no update / alter statement and therefore no error from a query either.
Hope that helps support analyze – I can grant access to you to analyze if you wish, please let me know.
Hope it also gives you a workaround lmccabe
Thanks,
Thiru