Try this PowerShell script:

$IcaclsExe = "$env:SystemRoot\System32\Icacls.exe"
$ThumbCacheFiles = "$Env:LocalAppData\Microsoft\Windows\Explorer\thumbcache_*.db"
& $IcaclsExe $ThumbCacheFiles /grant Everyone:F
Remove-Item -Force -ErrorAction SilentlyContinue $ThumbCacheFiles
Stop-Process -Force -ErrorAction SilentlyContinue -ProcessName Explorer

Finding a manual for the WE55UDT108 is a bit of a pain. I got no hits on westinghouseelectronics.com, but I did find what appears to be the correct manual here.

That manual states:

“USB Port: Connect to a USB storage device to play compatible movie and photo files.”

That makes sense. Most, if not all smart TVs have at least some ability to play movies from USB drives. Since the manual provides no details, I suggest some trial and error testing.

Place a few small video files (MP4, MKV, MOV) on a USB drive formatted FAT32 and see if that works. Then try again with the drive formatted ExFAT and see if that works. Try NTFS again (maybe use a different drive) and test that too. Something’s bound to work. And don’t use the same video files that failed before. Download something new (and small to save time).