I'm getting exactly the same issue.
My reason for wanting to do this, is so that the 'Capture MIDI' feature in Ableton is active; this feature drops off if the BSP is master
I've tried different midi channels - I've managed to isolate it to mapping the 'stop' button; once the 'stop' button is introduced I get the issue. [edit] If I map only the BSP 'play' button to the 'stop' transport in Ableton, I get the same issue when I play Ableton from GUI
I have latest BSP Firmware - 2.0.1
Ableton is current version - 10.1.9
I've attached a pic of my Ableton Midi Preferences