Spektrum SRXL with Cube FC

I am trying to connect a Spektrum AR8010T RX via SRXL to a Cube FC.

Using AC3.6.5 chibios and nutx the signal in mission planner is very jumpy and stops working after a few seconds. If I use AC3.4.2 it is still jumpy but doesn’t stop.

I have wired the connections as per HERE

Just wondering if there is anything that needs to be configured in the software.