If that is the case, it is almost certainly not running out of space for transcodes. In /var/log/jellyfin there should be FFMPEG log files. Check those out to see if they can give us insight into the problem.
Jellyfin 10.10.7 (Docker)
Ubuntu 24.04.2 LTS w/HWE
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
4x WD Red Pro 6TB CMR in RAIDZ1