Xeptu, correct me if I’m wrong..it’s been 40 years since I fiddled with a 331.
My memory of the NTS system is that it cycles the blade angle between feather and some other blade angle to minimise drag - where drag is the condition when the airflow is driving the engine.
The idea being that this feature buys the pilot time to recognise the failed engine and feather it.
I don’t understand how NTS, if working as intended, would flip anything on its back anymore than say stalling an aircraft with the operative engine producing power.
Is it possible that the fidelity of the simulator in question may be lacking at that extreme corner of the envelope?