Andrew.

I'm running Logic Pro 10.7.4
Mac OS Big Sur 11.7.2
BIAB MAC Ver 2022 (609)

FYI I also noticed the same phenomenon in BIAB Mac 2021.

I do not run the plug-in for Logic. I run separate Logic and BIAB instances on my MBP.
My normal workflow is to build a BIAB arrangement. using a small set of biab real tracks. Once I am happy i add additional real tracks (never know when you need an accordion) and export these tracks en masse to .wav files using the biab .wav selection.

Sometimes when I load these first set of tracks into my logic project, I find one or more of the tracks is an empty wav file. This behavior is not specific to the utility tracks.

As I work through my mixing/mastering in Logic I may decide to replace or augment a track.
From my open biab arrangement, I select various instruments & generate them on utility tracks. I then select the new track and drag it to the file Export area (under MASTER on the menu bar). BIAB seems to be "going through the motions" of generating the track. Once I get the green light on .wav selection I drag the file to my daw.

I have worked in this manner hundreds of time. Mostly it works just fine. Mostly. At times however I am rewarded with an empty wav file. I can't tell you whether it fails 10% or 30% of the time, I'm guessing closer to 10%, but enough to be annoying.

Let me know if I can provide you any additional information.

Thank you.

biab2023(Mac)
Logic Pro X