SMB/CIFS network share in Media folder not shown in all addons (e.g. Jellyfin)

Hi,

I have found the suggested way to mount a NAS via CIFS via shell command.
This works fine for the Media library included in Home Assistant but does not work for addons like Jellyfin.
There is the folder always empty.

Example config:

shell_command:
  mount_nas_multimedia_folder: mkdir -p /media/NAS; mount -t cifs //IP/Multimedia -v -o username=USER,password=PW /media/NAS

If I go to the docker console (via portainer addon) at Jellyfin, I see the following at ls:

root@db21ed7f-jellyfin:/# ls -lisa /media/NAS/
total 8
427112 4 drwxr-xr-x 2 root root 4096 Nov 25 12:55 .
131329 4 drwxr-xr-x 3 root root 4096 Nov 25 12:55 ..

The problem seems to be, that the mounted content is not accessible by the host itself (connected via -p 22222 ssh to host):

# ls -lisa /mnt/data/supervisor/media/NAS/
total 8
 427112      4 drwxr-xr-x    2 root     root          4096 Nov 25 11:55 .
 131329      4 drwxr-xr-x    3 root     root          4096 Nov 25 11:55 ..

Adding the mount to /etc/fstab at host will not work because of read-only filesystem.

Does anybody know a solution for that?

I am using a Home Assistant OS generic installation.

Thanks a lot and kind regards,
Daxi