I have an external sequencer which I'm using as the main clock source, the Pro 3 is receiving clock. When I start the external sequencer, with it sending transport too, the pro 3 doesn't always respond. It receives clock but the start/stop doesn't seem to reliably work.
With transport off from the external sequencer, I have to hit the play button on the Pro 3's sequencer so that it starts when the clock is sent to it, but then if I send a program change message it just stops playback on the Pro 3's sequencer after the new program is selected.
One of the main reasons I got the Pro 3 was for it's sequencer, but it seems sort of buggy via external MIDI.