Seconding tmsrxzar's #3. Network shares need to be mounted to the OS. You will have a much easier time getting Jellyfin to read it and permissions to work properly.
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