Not sure what’s going on with my pro.I've got a Bkool Pro and I've never experienced this problem in races. I've only done one workout ride and all was fine with that too. Sometimes I find a lack of resistance at the start of a ride, but I'e always found switching the trainer off at the plug and back on again sorts this out. There's already been plenty of discussion about the fact that the watts shown by the Bkool aren't always accurate and are often over-generous, but apart from this it works fine, and definitely never had the problem you describe.
Group workout on Zwift was impossible due to the resistance Jumped to maximum and was impossible even in my easiest gearing.
Same with a bkool class even the warm up gave me exactly the same issues.
I was spinning ok until the class started on bkool and then I noticed it went into auto mode.
I’ve tried switching on/off but it doesn’t seem to make any difference.