Subtitle ASS don't works

[Fate]

If you share your logs via pastebin, we would be able to make that determination.

Attached is the transcoding log for a film "A Beatiful Mind" (H264) which has subtitles in ASS format.
The player freezes.
Thanks

If freezes because your raspi cannot even transcode 1 frame per second. Let alone 24/30 fps.

Raspi is much to weak to do anything in software. It's a bad choice for Jellyfin.

Your only choice is to use a client that allows you to directplay content or buy something like an n100 minipc that can transcode via hardware.