I also just had this issue with a GP20 LC Plus engine on a 036 switch. It only occurred coming into the switch.  The switch was located coming out of a 036 curve.  I put a piece of straight track between the curve and switch and also performed the adjustment as noted above on the you tube video. It appears I have solved the problem as it has not derailed since. This was a left hand switch and only had problems with this one engine. I have right hand switches installed in curves without issues so I don't know why.  This occurred with two left hand switches in this same location because I thought it might be the switch.   Hope this helps.