XPlane 10 HITL Pixhawk Control Problem

Using the standard plane airframe developer build of PX4 and the daily build of QGroundControl, with sys_hitl set to 1. Upon connection and arming of the aircraft, throttle is commanded at some value above idle and impossible to change. Yaw is mapped to throttle up/down, and pitch/roll is reversed on the other RC stick. Remapping the channels in QGroundControl do not change this effect. Rebooting the pixhawk after every change. Any ideas why this could be?

Bug filed here. https://github.com/PX4/Firmware/issues/7794