So every time I import some music into the library, I test it and it sounds fine. Then I make a blank keyframe and drag and drop the music to the stage and it doesn't play anything. In the frame it's just a blank line.

Don't drag and drop it, to dont need too. Click the frame in your timeline to select it, go to your properties panel an pick the song in your sounds, then for the timeline functions select stream.

That's odd. If I change the music to event instead of stream, it plays.