I assume you used the ACW? If so, when you "sent" the chords to Biab, you should have had Biab ask you if you wanted to keep the tempo map that it deciphered. If the chord changes are not close to the original tempo in the ACW, Biab uses it's own to line them up.

When I use the ACW, I will look up the tempo (if available) on a sheet music site like musicnotes.com prior to importing into the ACW. You can also pre-set the audio tempo in Biab prior to import as well.

Trax