SDC2130s RC/Pulse input/closed loop problem

Hi. I'm trying to set up the 2130S to work in closed loop, driven by a ppm (RC) signal. I've managed to get the MDC1230 working well in this way, but I'm experiencing very erratic behaviour from the 2130S when I use the same approach.

I am able to read the ppm signal in the 2130S, providing I reset to factory defaults though the PC, power cycle without the usb connected( the status LED shows that its in RC mode)and then connect the USB to the computer. It is then in Open loop mode and i can control the motor direction.

As soon as I enable pot feedback for one of the analogue pins (AN4 on pin 11), the 2130S mode changes to 'idle' on the led indicators, and I cannot read the ppm input in either the calibration menu, or in the run window. This behaviour persists until I do a factory reset. After factory reset I am able to drive the motor using ppm in open loop. I am able to recreate this behaviour on 3 units. As I said, I am a bit stuck for how to resolve this behaviour, as the MDC1230 calibrated as expected.

I am using the 17 firmware (the latest), and also tried it with the previous firmware (V16).

thanks. here's the profile