I use my Stages G2 PowerMeter as the power source to Zwift, I have a Tacx Vortex Smart Trainer as the controllable trainer. When I used the Tacx as the power source, I never had any ANT+ dropouts but my Stages has a dropout perhaps once ot twice every hour. The reason for using my Stages is that the power transmitted by Tacx Vortex is way off compared with my Stages with both units calibrated as specified in their instructions. If in a race a dropout is rather frustrating as the power goes to 0 W and then you get dropped very quickly! I have tested with different locations for my ANT+ stick (Garmin) and at the moment it is on the floor right below my crank. I don’t think it’s the placement that causes the dropouts, I suspect some firmware bug in Stages but who knows? I have read that I’m not alone with this issue, it seems rather common.
Add a possibility to add a secondary power source in Zwift. If the primary source transmits 0 W (or perhaps below 10 W) and the secondary transmits valid values then Zwift could use the secondary power source until the primary power source is back in business again. I suppose Zwift in this scenario should listen to two power source ANT+ channels?