Hi,
I took the compulsory update Zwift this morning on my iPad.
This seems to have broken the cadence measurement when using with my Wattbike Atom (it was fine two days ago.)
The cadence now alternates between 87, 96 or 106 and doesn’t react quickly as I change pace.
Makes targeted training very difficult!
I don’t dispute that something strange is happening with your cadence, but I suggest that it is unlikely to have anyrhing to do with the Zwift update, i.e. it’s coincidental.
I say this for two reasons. Firstly, Zwift doesn’t calculate your cadence, it just takes whatever your trainer sends it and displays it. Secondly, lots of people use Wattbikes and there would be lots ot people posting about this if a Zwift update had broken this.
I suggest that you do some troubleshooting on the Wattbike itself, e.g. via their app, to see what’s going on with cadence. I believe that like most trainers the Wattbike only estimates cadence anyway and doesn’t have a built-in cadence sensor.
If it is jumping between specific numbers, normally points to another device connected to the WB at the same time.
Also if you are running the Beta firmware sack it off for now, as there are loads of issues knocking about with it.
I’ve had that. It’s definitely A Thing, but it’s definitely A Wattbike Thing, not A Zwift Thing and certainly not A Zwift Update Thing.
I think it might have been because my Atom had been left switched on for ages (overnight) btwn rides.
Anyway - closing everything down and switching everything off and then bringing everything back to life cleared it without fail.
I’ve had the same since that update. Did you find a fix?
My post immediately above yours (and Lee’s above that) should do the trick, but come back here and let us know if it doesn’t. 
It worked! Didn’t know I had to switch off the WattBike!