Not sure if I had the same problem. This morning I did a flight using the stock A320 Neo. The AI Pilot was flying it. High up in the air (20,000+ feet) the aircraft almost became inverted. Speed fluctuated between 150-250 knots. Engine power was almost always maxed out. The flight was very erratic. That was a flight over the UK. It looked like crazy winds. During the descent the A320 stabilised.