Sometime in the not too distant past, my "custom appearance" thumbnails have become all confused. They used to closely represent the colours and textures they contained. Now take a look at the attached screenshot.
Is there a way to reset these? I have about 40 custom appearances all up.
Just found and fixed the problem. A couple of temp files had found their way into that directory, I deleted them and most of them worked fine.
Very strange, but it tried to pick up the temp files as appearances. Those "aluminium machined_t1" and t2 files were the culprits.
I've still had to re-edit the appearances which use jpg files for their textures to restore the menu appearance.