I have a Nexus 10. I had cleaned out all of my MP3's in my (Google) Play Music in getting for some new stuff I'm going to be putting in. What I have found is that I have now deleted the MP3's that I had uploaded in MS to my coordinating sheet music. Is this actually supposed to happen? 
I upload the MP3 via the companion app from my laptop which is where I have the MP3's saved. Any suggestions?
I upload the MP3 via the companion app from my laptop which is where I have the MP3's saved. Any suggestions?