As I said before, if I can replicate the problem, I can fix it. Otherwise I have no idea what the problem is. There are a few bugs here and there in the alpha, but as far as I can tell, the players all load up fine.
Make sure you only have a single instance of Logitech Media Server running. If you have more than one squeezelite may be attached to the wrong server. And although you can queue songs, nothing will play as it's played on the wrong server.