Apple Music / CarPlay Interaction Problem

I've used CarPlay for years without this problem but have recently enabled Apple Music with iCloud Music Library and am seeing two issues regularly now when I'm driving my car. First off my configuration is:

Apple Music

iCloud Library Enabled

Cellular Data for Apple Music is off

CarPlay is in an up-to-date 2018 Audi A4

I have several playlists I listen to when I'm in my car including ones that were just iTunes playlists but also Apple Music playlists that are fully downloaded to my iPhone. I also have some playlists not downloaded to my iPhone but I don't try to play them in the car.

Problem #1:

I could be going along and listening to a playlist fine and then I decide to switch to a different playlist in the car but the playlists list is completely blank (see screen shots below). If I mess around with the radio, after a few minutes I can get the playlists to display. I did some experimenting in the garage with Wi-Fi on and off and this is only a problem with Wi-Fi off. Also, with WiFi off and NOT being connected to CarPlay, there doesn't seem to be an issue either. This seems to just be an interaction between Music with cellular data disabled and CarPlay.

Problem #2

Once in a while I am playing an Apple Music playlist and it just freezes and stops playing music. I can switch tracks but it keeps not being able to play anything. Again, after a few minutes it just starts working again on its own. I can't reproduce this at will so I'm not sure if it is also related to cellular data or not.

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