Folder thumbnail background turning black

Spent about 3 months tweaking this installation of directory opus after a clean reset of windows 10 and now I find I cannot have live folder thumbnails because every time I turn them on they will eventually gain a black background.
The same folder in windows explorer does not show them with black background.
I can easily fix the the problem (for a very short time) if I use Disk clean-up to delete the windows thumbnail cache.
It seems I might have to do a total reset of Directory Opus and start again with the the caveat never to toggle or play with the folder thumbnail options.
Is there some Directory Opus syatem file that I can delete/reset to save doing this that might fix the problem ?


It's an ancient Windows issue dating back to Windows Vista and still in Windows 11 that Microsoft are too incompetent to fix.

You'll see exactly the same thing in File Explorer.

Forcing the shell to regenerate the thumbnails can fix them (whether or not it happens is random each time, and the result is then cached by Windows).

You can also tell Opus to generate folder thumbnails itself instead of asking Windows for them, which avoids the bug in Windows but results in thumbnails which look different.