EDIT: HERE’S THE FIX THAT WORKED FOR ME:

I was using qView as a photo viewer. I uninstalled it with Bulk Crap Uninstaller, then I used ShellExView and ShellMenuView to disable every right click menu item that wasn’t from Microsoft, then I cleared the thumbcache and entered

Get-AppxPackage -allusers Microsoft.Windows.Photos | foreach {Add-AppxPackage -register “$($_.InstallLocation)\appxmanifest.xml” -DisableDevelopmentMode -ForceApplicationShutdown}

into a PowerShell window. It gave me an error message but made a popup come up saying I’ll be signed out in 10 mins. If I remember correctly I manually signed out and signed back in myself and nothing changed, but then the 10 mins went by and when my computer restarted, my thumbnails were back.

A laptop I used to use in 2011 would shut itself down automatically on a hot summer’s day due to overheating. It was an HP Pavilion, might have been built before 2011.

Update: Just before I stood up to take a break I discovered a weird way of getting it sort of working. If I disable Windows Indexing (by going into Services and disabling Windows Search) then I add affected folders to the exlusions list from the Settings panel, then open one of the pictures in said affected folder and hit F5 it displays the icons in like a minesweeper type way where the photo itself and all the photos around it within a small vicinity come back. What sucks is that when switching views it does not update and it either stays small when going large, or it stretches and pixelates.

If you know anything about Python you could probably set up something like OpenCV to detect your cat’s face and when it does, play a loud sound like you screaming “HEY!!! GET THE FUCK AWAY FROM THERE!!!” on your computer which you would hook up to some loud speakers.