Elements 2020 thumbnails do not show photo, only hourglass

[Oldharrah]

Elements 2020 organizer does not show photos in the thumbnails, only hourglass for photos after February 2022.  Have to enlarge to where there are only 4 or 8 photos in view.  Nothing new going on; same camera i have used to 10 years.  Photos from 2021 back to oldest display properly in thumbnail.  10 year old computer; Windows 10; 28,000 photos.

[Greg_S.]

What format of files are they?  Have you tried manually updating the thumbnail?  (Select a thumbnail and press Shift+Ctrl+U).