Have the same problem.
Need help here. Apple Music is in the brink of messing up my library of 40K+ of songs.
Over the weekend, on my iPhone 6+, i updated to Apple Music. Chose the Merge option since replace sounds too absolute. Apple Music integrated wonderfully with my existing songs and playlists.
When i got home Sunday, I tried to add songs and revise my playlists on my iMac. Now i do not have internet connection except on my mobile thus my iTunes on my iMac is not up to date. iTunes didn't allow me to add songs to my device with the prompt, "cannot add because this device it using iTunes Match". I did not subscribe to match but i understand that it came with Apple Music. With that i decided i didn't need Apple Music nor iCloud Music Library. I turned them off on my device. My whole previous library on my device got deleted.
Now I thought it must be an upgrade issue. I decided to back up some songs and playlists on an external hard disk which i plan to load on my phone using my Macbook Pro. I went to work using my Macbook Pro. At work i have pretty decent internet connection. On my Macbook Pro, i urged my iTunes to the latest available. Still I can't load my playlists on my iPhone using the latest version of iTunes. Upon loading my playlists, no songs were included therein. How do fix this problem?