PMS does not detect deleted externally music files

I have a root /media/audio/music that the library is mapped to (read only from zfs storage).

Inside this audio root directory there are many child folders of which many have more child folders. fully qualified it looks like this:
/media/audio/music/something/a
/media/audio/music/something/a/1
/media/audio/music/something/b (0 files)
/media/audio/music/something/b/1 (0 files)
/media/audio/music/something/b/1/I (2 files)
/media/audio/music/something/b/1/II (3 files)
/media/audio/music/something/c/ (80 files) ***
/media/audio/music/something/d/e/f/…
and so on…

I did delete the folder marked with a ***.
(Actually technically I just moved it completely outside the scope of /media/audio, so that PMS must think it to be deleted.)

But the rest of the library is intact, so there should be no reason, that PMS should think that the entire drive has become unavailable.

[Is there a technical limit definied when it comes to maximum path depths in which crawling/deletion detections is performed?]

It also doesn’t seem to be deterministic - I tried the same thing just a few minutes ago and then it worked ?!? I don’t know, it might have something to do with different Scanner / Agent settings (right now I am on the old “Plex Music Scanner” and Last.fm agent combination, because of this issue: Various Artists cover with Plex Scanner )
That might have an impact on why it worked now…
Or it might be due to the fact, that I upgraded the iocage jail from FreeBSD 11.3-RELEASE-p9 to 11.3-RELEASE-p10.

Very strange… I will continue watching, if it reoccurs *g