Shifter motor on DR4B becomes unresponsive after raising lift to maximum height

Hello, fellow Vex gods,
My teammate and I have had a trouble with one of our shifter motors that is connected to a splitter, as it becomes unresponsive after we raise our RD4B to its max height. I am curious if anyone here might have had a similar problem or know what causes this. After we lower the lift slightly, the motor begins working normally. There is also plenty of slack between the wires and the cortex.

By shifter motor, do you mean a 4 bar/chainbar/linear slide on top of the dr4b that “shifts” the cones for internal stacking?

Whatever it is, I would guess this is a code problem. When the lift is all the way up, there might be a loop the code is in, that makes the shifter not respond. when the lift is lower, that code loop isn’t active, so the shifter operates as expected.

You say there is plenty of slack on the wire, but it still seems like a wiring issue to me. Could be code, though, depending on how things work in your code.

Check to see if the motor wire solder has come lose and disconnects when the wire is in a certain position. I have had this happen to 3motors this year.