Hi Dan, I'm glad to hear that you got things working. To sum all this up:

GREEN = Audio Track
YELLOW = MIDI Track
BLUE = "Track (Audio or MIDI) is synced to DAW"
RED = "Track (Audio or MIDI) is muted"

*You cannot sync both Audio and MIDI tracks at the same time. This is because the plugin cannot output audio and midi together. So if an Audio track is synced (blue) then you can sync other audio tracks, BUT double clicking on a MIDI track will do nothing. If you want to sync MIDI tracks then make sure there are no Audio tracks selected. The same happens vice versa. I hope this helps!