Why can't the Files, or Music app, see my Local type External Storage pointing to my readable-by-all nfs mount on /mnt/music_all?

Why can’t the Files app, or Music app see my Local type External Storage pointing to my readable-by-all nfs mount on /mnt/music_all?

So, i have 4 music libraries located on another music server that need to stay separate, and since the Music all does not allow for setting multiple music SOURCES, i have aggregated the music by, on the remote machine i have set those 4 music libraries as individual nfs exports, and on the Nc (Nextcloud) server machine, i have mounted those four separate libraries as readable-by-EVERYONE, read-only, nfs mounts inside /mnt/music_all, like so:

/mnt/music_all/music_library_1
/mnt/music_all/music_library_2
/mnt/music_all/music_library_3
/mnt/music_all/music_library_4

All nfs mounts.
All read only (i do NOT trust other software not to damage my media).
All readable by everyone on the system.
ALL other apps on my Nc server can navigate and read this media with zero problems.

I have the parent directory ( /mnt/music_all ) set up as a Local External Storage under Nc admin’s global External Storage. In the Nc admin settings for External Storage, it shows up as being OK (green checkmark). I have this Nc External Storage created as “music_all”, read only, and i have it set as being accessable my Nc user group called “music”, and my 3 users are all in that “music” user group. I also have my user as having access to the “music_all” Local External Storage.

In Nc, the Files app shows the “music_all” folder, but when i navigate into it, there are no contents.

I also have the Nc Music app pointed to the Nc “music_all” External Storage as it’s root.

I don’t see any messages in the log explainaing why Nc refuses to look inside any of:

/mnt/music_all/music_library_1
/mnt/music_all/music_library_2
/mnt/music_all/music_library_3
/mnt/music_all/music_library_4

…but seems perfectly willing to look in /mnt/music/all

??