Plex Windows 10 app won't play music

I recently moved all my my music to my Plex server (bye Google Play Music), and it worked fine for a while. Then all of the sudden, I am unable to play anything through the Windows 10 universal app. Whenever I try to play a track, it’s stuck at 0:00 and pressing the Play button does nothing.

All my music plays fine through the web app, so it’s not the files or anything. I have this issue with the app on my Windows 10 PC and my Lumia 550 running Windows 10 Mobile.