See attached, occurred a few times tonight when creating thumbnail.
Wow that’s weird. Do you see the same thing in different browsers? Is it any model?
I did a bit of playing around, I can say
Here they are, not perfect formatting but hopefully OK.
“Sorry, the file you are trying to upload is not authorized (authorized extensions: jpg, jpeg, git, mov, mp4, png, gif, zip).” Why not pdf?
I suspect an issue with the gpu driver, so far we couldn’t reproduce on any device (and it doesn’t seem to be a widespread issue since I can’t recall any thumbnails with the same problems).
If the issue happens again, you can open the console to see if any warning/errors logs appeared.