Hello @ebrandz,
Sorry for the inconvenience.
Video thumbnail generation should work fine with the newly uploaded media.
Could you please specify if you are facing this issue with newly uploaded media or the already uploaded one?
If the issue exists with fresh uploads then let us know the format of the video as well.
Additionally, could you please share your website URL and link of the video for which you are facing thumbnail generation issue so that we can look into it?
Thank you.