Adding MP3s to a library with M4A broke metadata for TITLE on M4A files?

[lalala123456]

Server Version#: Version 1.23.6.4881

I’ve a music library for radio shows. Normally these are in m4a format but i’ve been filling gaps with mp3s.

On adding mp3s to the folder, on the next rescan it first split them into separate album artists (all > albums > album artists view) - I merged - then navigated into it, and it’s ignoring the title tags for the m4a files now:

Clicking edit against one of them shows the title tag is missing?!

Here’s a screenshot of a screenshot sent to a friend where the 2020-02-* ones were correct prior to adding mp3s:

The files are edited and tagged exactly the same for every tag you can think of, except the title.

Library settings:
Prefer local metadata: ON
Genres: Embedded Tags
Album Art: Local Files Only

Any ideas?

EDIT: Just scanned again and it’s removed the title for everything.

Plex Media Server Logs_2021-08-03_22-16-55.zip (994.2 KB)

[lalala123456]

Moved folder out of library path. Left overnight. Optimised DB (even though I’d tried optimising last night and rescanning). Let it scan on it’s 2 hourly cycle. Fixed.