I have recently done a lot of research on how to fix Google Play Music when it gets confused about your offline music libraries. In my case, I had to remove an SD card to restore some accidentally deleted pictures. Removal of sd card can easily confuse google music to the point that it needs serious help to refresh your library again. Using "Refresh" and "Clear Cache" from the the settings will do absolutely nothing to help with offline music collections. But this trick worked for me (some of this can be found in other posts, but the playlist part is unique and important)
1) Application Mgr->Google play music->force stop
2) Settings->Storage->eject sd card (this unmounts the card)
3) Launch Google play music
4) Your sd card songs should no longer appear, but there will be ghost copies of all your playlists that should have been only on your sd card. Delete ALL these playlists now by clicking on "..." for each and deleting. THIS IS IMPORTANT as google play music can have trouble recreating/syncing these files. These are not the real copies anyhow if you had the playlists on your sd card.
5) Application Mgr->Google play music->force stop
6) Settings->Storage->sd card (remount card: yes)
7) Launch Google play music and be patient as it rebuilds. This can take a while if you have thousands of songs and playlists.
No rebooting necessary! Although there is no telling how many times I tried rebooting in previous attempts to fix this issue. I almost switched to another player, but I use Android Auto, so it integrates with GPM... Probably better to learn and live with its deficiencies rather than switch.
1) Application Mgr->Google play music->force stop
2) Settings->Storage->eject sd card (this unmounts the card)
3) Launch Google play music
4) Your sd card songs should no longer appear, but there will be ghost copies of all your playlists that should have been only on your sd card. Delete ALL these playlists now by clicking on "..." for each and deleting. THIS IS IMPORTANT as google play music can have trouble recreating/syncing these files. These are not the real copies anyhow if you had the playlists on your sd card.
5) Application Mgr->Google play music->force stop
6) Settings->Storage->sd card (remount card: yes)
7) Launch Google play music and be patient as it rebuilds. This can take a while if you have thousands of songs and playlists.
No rebooting necessary! Although there is no telling how many times I tried rebooting in previous attempts to fix this issue. I almost switched to another player, but I use Android Auto, so it integrates with GPM... Probably better to learn and live with its deficiencies rather than switch.
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