Thank you Matt, thank you Jim.
Yes, I fiddled with the MIDI driver latency, but when BIAB detects my keyboard a message comes up telling me that the latency should be set to zero. I didn't go any further because the latency on the laptop that has BB2020 on it (and works okay) is set to zero.

This year, as with previous upgrades, I've loaded the new version on top of the current one. Generally the upgrade doesn't make any changes to preferences or settings. However, this year for the first time I purchased the upgrade only on the thumb driver, rather that the full version.
But I can't imagine that would have made any difference.

Cheers,
Keith