Kickr Snap Power drop at high speed (not power)

Backgroud: I’ve been using Zwift for c 10 months with no issues.  Connecting over Bluetooth using ZML.  Everything was good.

At the w/e I updated ZML (android) to the latest version (I understand this had been out some weeks previous). I immediately started to encounter LOTS of power drops.  I couldn’t ride more than 5 minutes without dropping.

Lots of research later and updating of Snap F/W and switching to ANT connection and selecting the FC-E version of the trainer and I thought all was good, I did an hours ride Tues with no drops.

Current issue - I tried the new Leith Hill route last night.  All was fine but, on the fast down hill section once my speed got above around 40mph my watts went to 0. I was still peddling, HR was still showing but watts remained at zero.  It was only after dropping cadence and slowing to around 30mph that the watts picked up again, first jumping to c800 then coming down to c200 (where I would expect).  This happened 2 or 3 times on the downhill (and later coming down on Fox hill.  I also tried a hard push on the flat and, similarly, once I got up into the 30mph zone at c 450w the trainer ‘cut out’ again with watts going to zero and I had to wait 20 or 30 seconds for it to slow before I started getting a reading again.

Does anyone have any idea what could be causing this?

Sim mode or ERG mode? Spin down completed?

Sim mode (I don’t use ERG at all so not tried with that)

Spindown and advanced Spindown done in the Wahoo app. When I rode before with no problems this is all I’d done (I didn’t do the Zwift one). 

When I was having all the problems after updating ZML I tried a Zwift spindown and found it no better so at the moment it is set up just with Wahoo advanced.

Its annoying as I thought it was fixed but it is just when either lots of watts go through or high speed that it drops.

You lose resistance when the power drops Phil?

Have you tried the non-FE-C ANT+ version of your trainer on the Zwift pairing screen?

No, everything stays the same, if I wasn’t looking at the screen I wouldn’t know that the watts had gone to zero (nor that they’d come back again).  I know that the connection is still there as my HR continues to show and that is fed via the same Ant connection.

When I first had problems after updating ZML I was trying the non FE-C ANT connection and that caused far more drop outs.  I just wish there was a way to roll back to the previous ZML, I used that for 10 months on BT with no drop outs whatsoever!  It didn’t occur to me when scrolling through my apps on google play and seeing that there was a ZML update from 7 weeks ago that updating to the latest version would cause so many problems!!

non-FE-C is going to be much worse than FE-C. It’s curious that the new ZML caused these issues as well.

I’m going to open a ticket for you and maybe we can get to the bottom of this.