Thumbnails are hourglass but photo shows if enlarged

[#1]

I have over 55,000 photos in PSE 2018 Organizer without issue but lately all the photos I add are only showing hourglass image for their thumbnails.  The full size images are fine and I can use all PSE functions.  The "update thumbnail" under the edit pull-down does not help.  I am using Windows 10.  Any suggestions on how to fix the problem would be greatly appreciated.

[#2]

Let's start with checking the size in pixels of those images?

https://helpx.adobe.com/photoshop-elements/kb/maximum-image-size-limits-photoshop.html

[#3]

The jpg files range in size from under 1 MB to about 10 MB with pixel counts from 2 to 20 M-- nothing larger than I have already running successfully.

[#4]

Any ideas on a solution?

[#5 · Accepted solution]

Using their online chat, Adobe was able to find me a solution.  Simply go to File/Manage Catalogs/Repair and an error message was presented about an error in the thumbnail cache. Answering yes to delete the cache and rebuild it solved the problem.