PBS GC tasks failing: Permission denied

[briantheimpaler]

Hey all,
I'm running PBS and I'm having an issue with the garbage collection tasks failing consistently.
The destination datastore is an SMB share on a QNAP NAS that I have mounted on PBS via fstab. The backups run just fine but when the GC tasks try to run I'm getting "TASK ERROR: unexpected error on datastore traversal: Permission denied (os error 13)".

I'm unable to find any permissions issues though. The share is owned by the "backup" user on QNAP, on PBS it's mounted with:

//brian-nas.<redacted>.com/Backup    /mnt/brian-nas    cifs defaults,credentials=/root/.secrets/brian-nas,uid=34,gid=34 0 0

With UID/GID 34 corresponding to the "backup" user on PBS.
And here's the directory structure as seen from the PBS host:

root@pbs-nas:~# ls -la /mnt
total 12
drwxr-xr-x  4 root   root   4096 Nov 28 20:49 .
drwxr-xr-x 18 root   root   4096 Nov 28 20:23 ..
drwxr-xr-x  2 backup backup    0 Oct  8 22:43 brian-nas
drwxr-xr-x  3 backup backup 4096 Nov 28 20:49 dummy
root@pbs-nas:~# ls -la /mnt/brian-nas/
total 220
drwxr-xr-x 2 backup backup      0 Oct  8 22:43 .
drwxr-xr-x 4 root   root     4096 Nov 28 20:49 ..
drwxr-xr-x 2 backup backup      0 Oct  8 20:53 .chunks
-rwxr-xr-x 1 backup backup      0 Oct  8 20:45 .lock
drwxr-xr-x 2 backup backup      0 Oct  8 22:43 ns

(Output trimmed)
I followed the guidance on another post on the forum. I disabled the Recycle Bin function for this directory on the NAS but no joy.

What else could I be doing wrong here?