If I understand your question, I think this has been fixed.

There is a Bar Offsite you can set which will move the start of the BIAB VST song to synch with where you want it to start in the DAW. This will remove the two bar lead in if it is present. Or if you render the file in the VST, you can simply remove the leadin bars (which you can also do back in BIAB).

Is that what you are looking for?

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BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6