Lloyd,
I was interested in your guide to getting the rendered video to work in time to the beat. Unfortunately I was not able to follow the steps exactly as you described, perhaps because of the procedure used in different versions of BiaB. I couldn't really see how this process could work any differently from the straightforward save, but hey, anything to get this to work so I tried as best I could to follow in your footsteps.

1. I couldn't just Save As > Save as video because that option is not available. It IS available if I select Save Special and save as an mp4 but that gives me no option to save as a chordsheet. I had to use the track buttons on the menu bar but even the Master does not allow a Render to video (although the 2020 Manual states that it can). So I had to select one of the other tracks and the right-click > Render Video(s) and then select Chordsheet in the dialog.
2. I then used Ctrl-T to get the minimal menu
3. OK to Render Video, name and save
4. After rendering I click on the Show Video File
5 Before I view I close the Make Video dialog and BiaB
6. I view the file and guess what ... No change.

This obviously does work because I have a video from someone who has done it. I have tried the other suggestions but to no avail but I really think I need to go back and look at my audio configuration again.