I second adding support for Favouriting , in addition or instead of star ratings. Whilst I prefer star ratings personally, Apple Music Cloud Libraries do NOT sync 3rd party ratings (ie made via the SDK api) back to the cloud. Marvis Pro is the same (and lets you set to show ratings as readonly if desired due to this apple bug). Ive also confirmed this myself with an app I wrote back when they hid star ratings completely. So I relunctantly switched to the favourites heart. Would be great to be able to flag a track in LongPlay with the heart too.

On a side note: even Apple doesn’t embrace album “favorite” functionality. Every couple days I discover that some of my albums have lost their “favorite” marking. It was reported to Apple many times by many people but they doesn’t seem to bother.

So I just created “Loved” collection in the Longplay app and added albums manually. And I feel much safer with that approach than if Longplay relied on Apple’s faulty functionality