Some subfolders on a mounted share inaccessible

Yes, but it didn’t make a difference unfortunately.

Thanks, I’ll give that a go and see if it works :+1:

I don’t use LibreElec but a quick search indicates that the default SSH logon is to root, so perhaps all processes run as root. I hope someone else can confirm / deny this hypothesis. If LibreElec processes run as root, that would explain why you have no problem accessing the files from LE. By contrast, on OSMC Kodi runs under the user “osmc” (UID 1000, GID 1000)

I also don’t have any experience of QNAP – or Synology, for that matter – but I noticed that you have set Guest Access Rights to “Deny Access”. Did you ever try “Read Only” or something the that effect?

AFAICT, you should be able to SSH to your QNAP box, since it’s a Linux-based device. So try to logon and run these commands:

exportfs -v
ls -la /Multimedia
ls -la "/Multimedia/TV Shows"
cat /etc/passwd

(Please copy/paste the results, rather than providing a screenshot.)

Edit: to comment on this bit:

Don’t forget to first rename the original “TV Teens” to “TV Teens OLD” (or something along those lines). As far as OSMC is concerned, this should work without the need to resort to path substitution. (Remember to reboot both devices.) However, I guess there’s always a risk that it might adversely affect the QNAP user interface,

I don’t have an opinion on if that is the way to go but just to throw in a FYI regarding moving sources…

That could be a good explanation and that would also explain why now change to squash_all_users doesn’t make a difference. So only solution there is set squash_all_users (at which time it should also not be accessable from LibreElec) and then onetime change the user of the folder directly on QNAP from root.