I rode a race today and twice I had a sudden drop in speed even though my power numbers were fine. Yes, there was a 4-5% bump, but I went from 37mph to 7mph in 5 seconds while pedaling 300W. It also looked like I got suddenly catapulted backward out of the peloton.
I think there is a bug in the speed algorithm/formula.
Attached is how it looks on Strava.
Are you using Zwift Play Controllers?
Yes, I do, but I didn’t touch them.
What trainer etc are you using?
A Wahoo KickR (about 2018) and MacBook Pro.
This does sound suspiciously like controllers braking. I bet that’s in the log; if so Zwift support should be able to confirm if that’s the reason.
Yeah, it does sound like braking. Thanks, guys, for hinting me in that direction. I just got them and I was convinced that I didn’t touch them, but with hypoxia, I don’t trust myself on that. I’ll watch out for that in the future.
I feel stupid though. “HEY, I SLOWED DOWN” … “Yeah, that happens when you brake” 
