Welcome to the forum.

If you're playing a Maj7(#11), you know your stuff.

That particular one is indeed missing. The closest workaround is BbMaj9#11

You can see what BIAB supports, and the occasional variant spelling, for all chords this way:

Right-click in the Chordsheet and select Chord Builder.
Find the pulldown under the buttons for 13 and 7b9 that has Maj as the default.
You'll see all possible supported chord extensions there.


BIAB 2026 Win Audiophile. Software: Fender Studio One 8, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Fender Quantom HD8 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.