Bob:

Are you using the 2022 version of BIAB?
When I click on either the "Audio Edit" icon or the "Audio Chord Wizard" icon,
the display shows multiple bars BEFORE bar 1.

The ACW shows a "blank" unnumbered bar, then bar 0 (zero) before getting to bar 1.
Similarly, the Piano Roll window starts at bar -1, then 0, then 1.

(Aside)
I'm not sure how Matt plays O Shenandoah. If he ignores the pickup bar, he must not play that first note! LOL

LLOYD S