Whoops, I realized I was missing the Media Monkey plugin in the requirements. Please ignore my post above!
Everything is working now except the currently playing section. It shows the same song currently playing even when I start a new one, and I'm unable to pause it (but volume and seeking to a specific time work just fine). Any thoughts?
Edit: Actually I'm getting a lot of issues with connectivity. If I restart musicbee and reset the connection, everything functions ok. But once I select a new song to play, the Play/Pause/Skip Track/Seek/etc. buttons all stop functioning. Soon after that it stops being able to pull up artists and songs. If I restart MusicBee it will work again, but only for 30 seconds or so. If I try to reset the connection on Retune without restarting MusicBee, the progress wheel will just keep spinning and nothing happens.