@TeamYouTube hey, every time I try to upload a custom thumbnail for my video it keeps going back to the one that was autoselected. I can tell the upload was successful as when I click “download” I am able to see the custom thumbnail. I have attached videopic.twitter.com/fYCiAvrheR
Thanks for the report, we've seen similar reports and are looking into it. In the meantime, you may try re-uploading the thumbnail to see if that helps. Appreciate your patience while we get this fixed.