Suddenly unable to edit fields

I just discovered I am no longer able to edit existing fields in any of my forms. Clicking on the cog wheel to edit the field just results in a spinning wheel. However, I can add new fields and edit fields in these newly added fields. 

I have recently updated Joomla to version 5. I have not edited forms for a while, so the situation may result from the upgrade, but I really can't say.

Any ideas?

I did, and it worked. Thanks :-)