There are several old threads discussing the possible work-arounds. The most recent is this thread:

https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=588344#Post588344

The workaround described is awkward, but doable.

I have actually saved an old version of BIAB for windows (running in Parallel Desktop) to use for just transposing stuff I'm working on into all 12 keys. Also awkward, but slightly faster when transposing multiple files.

Good luck, and keep asking PGMusic to please implement this functionality in a forthcoming patch release!

/Björn