I’ve been having similar issues with my H2, also via Android and Bluetooth.
Zwift seems to lose connection to the trainer, and doesn’t seem to automatically reconnect (or at least takes longer to reconnect than my patience can handle during a race/workout), so I need to hurriedly go to the menu, deselect the power source and re-select, and back to the game. Zero issues with the cadence or HR sensors, and I’ve never needed to deselect-select the controllable (which is the same H2 as the power source).
Sometimes it will work perfectly, but then there is the odd dropout (seemingly always at the worst possible time in a race, or right before a hard section in a workout 
). I’m not sure I’ve ever seen it happen during a free ride, but could be wrong. I have seen it in a meetup.
For example, on Tuesday I did a ride on Rouvy AR, and later the evening on Zwift a 3R race. Both worked flawlessly, no dropouts that I saw.
Wednesday evening, on Zwift the SSAT race, dropout just before 10 minutes in, goodbye bunch! Yet in the Alex Dowsett group workout directly after, no dropouts (I didn’t even log out and save, just “Join now” to go directly from Innsbruck to Yorkshire).
All this on the same tablet, in the same position, with my phone’s bluetooth and wifi turned off just in case.
In fact, if anything the Dowsett workout should have been more likely to get a dropout, given I turned on the TV to watch his session on Youtube at the same time.
The same behavior happens with my wife’s tablet, and with my previous tablet. Trainer on latest firmware, and the tablets on various Android versions (Wife’s on Android 7, my old tablet on 8.1, and my current tablet on 10).
No microwaves being used, or other devices that could be trying to connect to the trainer at the same time (Edge 530 is connected to the same cadence and HR, but different powermeter, and via ANT+).
From Zwiftpower, the section with the dropout. The part where both read 0 is a downhill section where I stopped pedalling. Then just before the dropout, the H2 power flattens out. The hiccup in between, I assume is where I am re-selecting it in the menu.
What I still need to test, is connecting the 530 to the trainer over ANT+, to see if the dropout occurs on both protocols at the same time. If it does, then possibly something with the trainer itself, firmware issue maybe.
Edit: Just to add - while obviously frustrating, and it would be great if we could figure out the problem (be it Zwift, Saris, or environmental), I’ll continue to race/do workouts. 40th or 68th in a virtual race, great workout either way.
