Why would you store MP3 on your PC Hard drive, and on your phone? That defeats of the purpose of the app. The app will automatically pull the files from your PC, and store them locally in your storage memory (proprietary file format of course.
The problem is that if music is added to Spotify via app on PC hard drive, the app no longer pulls the files from the PC (tested today) and those songs in the playlist are listed as grey. I don't care if they are added via android or desktop, I just want to be able to listen via android, but spotify won't play music that I own, only what is in their service.
Thanks... I did a forum search.. searched the support links, etc.. and no luck. So, thanks a lot for the direct link within the FAQ. I also had an issue with my mobile WiFi hotspot... I had device to device communications turned off. >.>
The main issue is that Spotify should be able to scan the phone's media files and fill in playlists, *then* pull what isn't on the phone from the desktop client as needed. (Some people do have their songs on both places, because of things like data caps, no connectivity, etc.)
edit: Plus, I don't put every single one of my music files on my phone in playlists.