EXT4 drive PMS: failure detected. Read/write access is required for path

Hello there,

I have been using my Plex container for about a year now and it was working very well, until I filled up all my storage (0 bytes left). This was the same drive my docker data was on and my Plex container config data.
Now when I create a new Plex container (even with a new clean config folder) on the drive I get the following error: PMS: failure detected. Read/write access is required for path in the Docker logs. When I don’t put the config folder on the mounted ext4 drive I don’t get the error.
The fstab line for the drive looks like this PARTUUID=e2f1e9bb-xxxx-xxxx-xxxx-xxxxxxxxxxxx /mnt/data ext4 defaults 0 0.
The command I used test where it was possible to put the config folder was docker run --net=host -e PUID=1000 -e PGID=1000 -e VERSION=docker -v '/home/pi/plex:/config' ghcr.io/linuxserver/plex (works) and docker run --net=host -e PUID=1000 -e PGID=1000 -e VERSION=docker -v '/mnt/data/appdata/plex_test_5:/config' ghcr.io/linuxserver/plex (doesn’t work)
The config folder is populated and it readable by the abc user when I exec into the container.

Do you have any ideas?
Tim