OK, is the app's speed control going way up when this happens? We need more details to figure out what's happening here. I fear he's just giving general descriptions of something from memory that might be unrelated.
When I've had an engine go into conventional mode, it has actually stopped first, and then accelerated to track voltage speeds. So it was easy to tell what happened.
Is this happening at certain area(s) of the layout? like over switches?
You need to furnish us with exact details. Can you duplicate this happening whenever you choose?
