Fix only half of files showing thumbnails & half showing icons

Hi, you could try e.g.
Clear and Reset Thumbnail Cache in Windows 10

and consider increasing the cache size:
Change Icon Cache Size in Windows 11 and 10

I might suggest:

Uncheck "Display file icon on thumbnails" in explorer view options.

Open Folder Options in Windows 10


The issue seems to be file extension jpeg and not jpg so check file associations for both and if different set default program for jpeg to whatever you're using for jpg.

Choose Default Apps in Windows 10

Perhaps
Rebuild Icon Cache in Windows 10

set default as Viewprint

What's Viewprint?

You can reset default association for jpg/jpeg using the appropriate option:
Restore Default File Type Associations in Windows 10

Check your image viewer for options that might control thumbnail settings. What is your image viewer (for jpeg files)?

Seems to be an issue with:

VuePrint

Set some other image viewer as default.

It's not updated since 2o14.

I just installed it. I cannot get to the program's options via the built in Menu. F7 for options does nothing. I also cannot easily set it as default image viewer so you must have maybe used OpenWithAdd or something to register it.

All I can say is that the icon you see on thumbnails belongs to that program. It also offers to install vueicons.

I'd suggest uninstalling it and setting another program as default. Then reboot.

Check your thumbnails. If they display okay - reinstall VuePrint and see if the issue returns, If it does, blame the program.