"Go to marker" drops a track

I have setup a single song in Mainstage with markers. I have also assigned buttons to use "Go to marker" so I can navigate around the song (verse, chorus, bridge etc.) but... if I go from verse into chorus without manually choosing the marker, there is an arpeggio track, which I can hear fine. If, however, I go into the bridge and press a button which does "Go to marker" for the chorus, the chorus plays but without the argeggio track.

I have checked the marker settings in Logic Pro (where they come from) and they are all exactly at the start of the bar, as is the arppeggio track in the chorus, so I don't know why this would happen. The playback settings are all "Sync: on", "Snap to: marker", "Play from: current marker", "Start with play action".

Does anyone know why this might happen? A side issue that might be relevant, the selection control very briefly shows it playing the next marker before it goes back to the selected marker, even if the "Go to marker" is pressed ages before the current marker is finishing.

Thx