I may be late to the discussion here but here’s my take on your race data. Firstly, your race VI is high which is around 1.15 versus the 1.06 that BBS estimated. The thing is, it’s not normalised power that dictates the result or time of your split. It is your average power. I’ve tried using BBS before and after a few tries I noticed that it’s hard to hit a low VI especially on hilly races.
There may be other factors here but it’s the VI that struck me the most.