Same here but with a much lower power rig (see below). I was however pleasantly surprised when I received my G2 a couple weeks back that the performance for me is generally really good with many MSFS options on high or even ultra!
Like others, no solution to this issue but only experiencing it once or twice a flight. One thing I have noticed is that it seems to coincide with a sideways head movement (possibly rapid movement) for example I sometimes notice a flash out of the corner of my eye and when I react to this by moving my head to see where it came from the headset will go black for a few seconds. Might have something to do with the tracking system and the system trying to figure out where my head is looking to generate the graphics??? I need to do more testing.
CPU- Intel i7 8700K
GPU- ASUS GTX 1070 Ti
RAM- 32GB