I’ve had this happen several times now and don’t see any rhyme or reason to what’s happening.
When editing MIDI parts in the Key Editor it automatically Record Enables the associated Instrument Track (side rant: which I hate, there really should be a preference to turn that behavior off - don’t record enable anything without my explicitly asking for it. It’s just presumptuous and rude 
). Normally when you stop editing the part Record Enable gets turned off for the track. But sometimes the track remains Record Enabled after editing and when that happens I can’t effectively turn it off. If I click on the button and turn it off it temporarily goes off. If I then start playback it remains off. But when I stop playback, the enable buttons light up again. This can happen on one or several tracks at a time. I suspect somehow the track(s) are never informed that the the editor has been closed - but who knows.
And yes I have set the preferences to not record enable selected tracks. And this is occurring on tracks that are not selected anyway.
There is one way to make this stop happening, but it is annoying. If I manually turn off Record Enable, save the project, close the project and then re-open the project the problem goes away.