Jellyfin picking same thumbnail for every video in folder

[odekath]

I downloaded a couple of youtube videos using YoutubeDL-Material (which uses yt-dlp) and copied the corresponding mp4 files, info.json and image files (webp) into my library. Jellyfin imports the videos just fine but assigns the image of the first video added to ALL videos in that folder. I installed the youtube-metadata-plugin but that doesn't seem to do anything.

Any pointers on how to fix this?

[odekath]

Found the issue: When the Thumbnails are present as .webp Jellyfin picks the first one it finds for every item in the folder. After converting the thumbs to .jpeg it works as expected.