Hi, just chipping in here...
I'm using a Roland FA-06 and USB Midi/Audio and experience the same problem when the synth is simultaneously sending midi data on several midi channels (i.e. ch 1,2,3), BIAB chokes on incoming MIDI and eventually stops.

Using a patch/sound that only send on MIDI channel 1 works fine.

The above-mentioned fix setting "no MIDI/sound input" works for multichannel, but then I lose the ability to input chords via the keyboard.

This works in BIAB 2020, so something has happened down the road.