MIDI track not playing sound anymore (OSX)

Okay so, I’m new to Cubase (switched from Ableton - and I still hate Cubase, but I’ll give it two weeks to adapt. It’s normal when you switch DAWs haha).

Anyway, I’m creating a Christmas piano suite, and all of a sudden the bass track (of the piano) has stopped outputting any volume.

What’s weird is, when the track is selected, I can play on my MIDI keyboard and it outputs sound fine. Also, when the track is SOLO’d, it outputs what it’s supposed to. It’s just when I unsolo it and let the composition play by itself, nothing comes through the bass track.

I’ve attached the problem in GIF format so anyone that wants to help can see what’s actually going on. Also here’s the link to the GIF of the problem in question:


Any ideas what could have gone wrong? I’ve tried undoing (cmd + z) to the point where the bass track WAS working, but no luck.

EDIT: Pay special attention to when I solo and un solo the track in the GIF.

EDIT #2: I just fixed the problem by creating a totally new track with the same instrument loaded in, and copied and pasted the MIDI data from the “non-working” track, and it fixed the problem. BUT I would still like to know WHY this may have happened, as it was annoying, and could be in the future.