web part – SharePoint 365 Classic Webpart Collapsed List NOT Expanding on Click

This problematic Webpart is on about a hundred of my webpages (classic) and it worked just fine until recently.

I have a main list of emails. From this list, the Webpart filters specific emails to a list on each webpage and groups the emails by sender. If the Webpart defaults to expanded view, it works fine (I can expand and collapse the view without issue). But if the Webpart defaults to collapsed view, I can’t expand the view. This is for all emails on all webpages.

I’ve had a ticket open for this with Microsoft and they have not been able to figure out why this is happening. Does anyone else have this issue? Has anyone found a resolve?

NOTE: I had the Webpart in the Miscellanous folder and, at the suggestion of the Microsoft Tech, moved the Webpart to the default folder. The results are the same.

Thank you.