My setup:
Using Podman (Redhat's version of Docker) containers. I have all the songs already on my backup NAS so instead of having them twice, I don't use upload import to get them into Funkwhale. I use this command instead:
podman exec api funkwhale-manage import_files {LIB_ID} "/srv/funkwhale/data/music" --recursive --noinput --in-place
Generally speaking this works more or less perfectly. (Takes tens of minutes, but it works)
There's a song that (somehow) is not associated with any library. I checked and the song hasn't been deleted - it's still in the path that's being imported in place. However, when I look at the import logs it says it can't import it because it's already there. So it seems to be in this place where funkwhale can't play it because it's not part of any library, but funkwhale can't import it because it's already known by funkwhale. I imagine one potentially easy fix is to delete it from the django admin, but I wasn't sure if there was a better way to fix this. (especially since this probably isn't the only song, I just happened to notice because it's one of my favorited songs)