Apple Music on MacBook Air is always 'updating music library' - but never gets there!

I've added 2 tracks to Apple Music on my MacBook Air (13 inch, 2017) of original music. I pay for iTunes Match every year so I have everything up there in the cloud - but the tracks have never appeared on my iPhone Music app / elsewhere.

The Apple Music app on my MacBook just says 'Updating Cloud Music Library' and has done for a week. I have fast internet and have left the computer running overnight to see if it just needs time, but that doesn't seem to get it there. I've not had this problem before. What's up?