There was a bug reported in the latest version of Onsong, not sure if this could be related
There is also a setting on the BeatBuddy in version 4.1.3 that changes how the Device opens Playlists
4.1.3 is now available at the top of this thread
Go to Main Pedal > MIDI Settings > MIDI IN > Program Change (PC) and select the one that works best for you
For Aeros mode, the sacrifice is that you lose the ability to open any song that is in or after folder no. 111 and cannot control any MSB banks. This is because LSB 111-128 control the Playlists on the BeatBuddy and MSB is ignored.
If you prefer this please switch to Aeros mode, this was how it worked by default in 4.0.1.
In default mode, you can open playlist songs using MSB 127 LSB 127 PC0-127