Yes you're right - it requires one Start message for the session. After that it will play synced. You can then change patches, edit the sequencer etc. and it still syncs. In my setup I "accidentally" receive a Start message anyway, and it gets going after that, as in it's almost hard not too in a general master/slave setup (I'd have to pull cables during Start/Stop messages to make that happen). So a single Start message is the workaround, but it's not ideal of course.