Cooltouch is absolutely right. BIAB has three chord types that are all implemented as a 2 chord. The following is part of the contents of the file /BB/Data/pgshortc.txt where this is clear. I highlighted the 2 chords:

Note these are already defined in BB, and you can't over-ride these shortcuts
;sus2@2 add2@2 m+@m#5 dim7@dim 7aug@7+ sus4@sus 11@9sus 9sus4@9sus
;13sus4@13sus add9@2 7sus4@7sus s@7sus h@m7b5 d@dim J@MAJ7
; f@7b9 m7+@m7#5 NC@C. no chord l@7Alt u@(Blues) 7u@7(Blues)
; Lyd@lydian Lyd@lyd Lyd@4#


BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.