Edit: The update I talked about is now released, so this should be fixed :)

Thanks!

So, there are two ways thumbnail generation works. One is via asking the server for one, and one is via downloading part of the video locally. Right now it tries both and stops when the first one loads.

Next update, I am going to change that behavior to always only use the server one, and only try local generation if the server hasn't responded in some time.

I also noticed a bug where sometimes local generation downloads the video multiple times, which might be amplifying the issue.

So, hopefully this issue will be fixed in the next update and you can try again then! thanks!