I just confirmed that creating a new driver profile resolves the missing music function, and coincidentally resolved, at least for now, some other bizzare UI bugs I've accumulated.
It's possible that certain bugs are linked to user profile handling, which could explain why some users experiences are different from others. Also possible that resource leakage is in the user memory space, separate from system memory, assuming Android OS has such separation. If so, then bugs randomly popping into user space could be temporarily cleared by refreshing driver profiles at certain intervals, until Lucid resolves the root cause(s). Most custom settings took 2-3 minutes to re-set, with exception of navigation Favs, which sucks to lose every time. But music is working now and I know how to get it back if it happens again, small victory today over Gravlins , a.k.a. Gravity gremlins.