I had this problem constantly on 2 Miprom 21's out of a 3 car group. They had Digital DC Drives, we would get entrapments in the overhead, car stuck a few inches above the top floor, etc...

We found a loose INR wire (it was the inspection circuit-not sure if its called INR but I think so), that wire was loose- all the way at the top of the controller with all those bad terminal blocks.

We tightened that up problem went away- we also put a toggle switch there to make putting car on MR inspection easier.