Linked Character Is Missing Animation Actions

Tldr: If I make a new blend file and link a “master character.blend” file to it, some of the animation actions are missing.

Also, if I make any new animation actions in the new blend file, can I add them to the master_character.blend file?

Details:
I use Blender 2.9 LTS. (if Blender 3 fixes this, let me know. I just don’t wanna switch to new blender unless it has a feature I really want).

I regularly change the master file e.g. improve the mesh, add costumes, etc.

The idea is to use the master_character.blend in different “short animated films”, each short film being a different blend file.
I want to use NLA strips to animate these “short films” (even if that’s not what NLAs are for. It’s just much easier adding a bunch of NLAs than making ONE REALLY LONG animation action for the entire short film.

p.s. if there’s a better thread to post this in, let me know or move this post to that thread.

Did you give the actions a fake user before saving?

Yes. I usually save a fake user for all my actions. Still missing lots of actions.