EDIT: Tl;DR
PlayerPro can modify and read the Windows Media Player star rating.
I've verified that tracks with less than 4 stars are removed from my device. However, I expected to see more removals. I'll continue to update here
I had an issue with PlayerPro, the 'stars' (rating) disappeared from the top of the screen. I solved this by tapping the track picture in the center of the screen. The star rating on top of the screen reappears after that.
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Awesome threat.. Just got a Nokia 9, first Android phone
Same issue.
I manage my music with auto playlist and star rating since I had a HTC Wizard and Windows XP, I think
Anyway, PlayerPro seem the way to go.
The problem I now have is that I can't seem to change the star rating anymore, in PlayerPro.
This:
https://www.aplayerpro.com/forum/viewtopic.php?f=4&t=3305
.. seem to be hopeful but alas. I'll continue the quest on a later day and update here.