Android MTP sync - .is_audio_player is hidden
On newer Android versions (at least 10 & 11 on my Galaxy S10e), the MTP protocol doesn't show hidden or "dot" files such as .is_audio_player. So if we could have an "is_audio_player" without the preceding "dot," then I think it would work.
So for devices with large disks, it takes forever to pull up the files on the device, because it not only looks at the Music/ folder, but all folders.
Additionally, it can't sync playlists in the correct format because it can't read the .is_audio_player file. Similarly, it doesn't know the file types it is capable of supporting.
And for some reason, most of the playlists I have don't show up as available to sync to begin with.
So again, I think that if Rhythmbox could not only look for the .is_audio_player file, but also one without the dot "is_audio_player", then it would work better.