The only post that might come close to helping was by rDin at Loopers compatible with the BeatBuddy - #3 by rDin
Although it was for an RC-300 which several users have figured out how to somewhat work, it leaves me thinking that this has more to do with Boss’ MIDI idiosyncrasies than with with the BB. I’m sure that if Singular knew the answer, they would have responded by now.