[lancorp]

Currently, I have a flat system whereby all my music is under Music on my 1520. No subfolders.

Today I added a folder (album) by connecting my phone to my PC via USB and copying the folder to the Music folder.
I checked my Xbox Music app, and the songs are not there. I gave it some time...no songs added.

Does the Xbox Music app search subfolders under Music for songs?

[user928]

Yes. But the "Album" folder is an internal folder created by the app.
Try this folder structure: Music > Artist > Album Name
Put the songs from the album in the folder. Disconnect phone from PC. The music app will get album info from the meta data in your mp3 files, if it is there, or from the internet, if you have configured it to do so. The music app should, then, create an "Album" folder with cover art, etc.