On my Edge 830 connected via ANT+ and Zwift connected via Bluetooth.
I experiences a lot of drop out on both Edge 830 and Bluetooth on Zwift.
Tried to swtich both to ANT+ or Bluetooth, but it didn't help. Tried it on mye Fenix 6 later, same story.
And it had a unstable connection on GCM app.
I tried to take out the battery for a few minutes, and that fixed the problem.
Read in another thread that there is a problem with stor and forward, that behave simulere to this. Therefore I thing they are related problems.
* At the end of the graf it has a stable connection, because I switched to my HRM-Run strap.