Give it awhile to update, sometimes youtube takes its time to update thumbnails
If it still doesn't update, check if its chrome thats playing up (or whatever internet you use), or go into edit & click on one of the chosen thumbnails for you, save it, then upload your custom tn again.
Hope it helped!
Thank youWhat's weird is all of the thumbnails went grey as soon as I made it public.
I re-uploaded the custom thumbnail again, and it fixed the video in the subscription box, but not the other platforms where it is posted.
Hopefully it updates soon. Thanks again for the suggestion!![]()