I was having similar issues with a couple of my locos. I noticed a particular loco would only stop on a turn out going a certain direction on either a facing point or trailing point. I found that one of the pickup/ contact wires on one of the trucks had come unconnected. I use dead frog turn outs and the loco would stall out on the frog on the side that the wire was disconnected.
Just something to check.
Just something to check.