A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi E.H.H.
Thanks for sharing your experience with us, we will help you do troubleshooting for the issue.
The Asset Library uses a Thumbnails view by default, which displays small thumbnails of the assets in the library.
If you are in modern experience, you may check if you select Tiles for Thumbnails view as below and see if you can view files:
We also suggest you check following:
1.Use the private mode of the current browser and go to the Asset library to check the outcome.
Use different browsers to see if there is any difference.
2.In the same site, create a new Asset library via Settings>Add an app>Asset Library. Upload some images to the library and see if they display in thumbnails.
If issue persists, we would appreciate if you share with us following information:
1.A full screenshot of the situation in your asset library.
2.Does the issue happen in a specific asset library? Does it happen to some specific files?
3.What is the file size you upload?
Best Regards,
Tina