Kerbal Version: 1.12.5.3190 (WindowsPlayer x86) en-us
MechJeb Version: 2.14.3.0-1326 dev
Other Mods: GravityTurn 1.12.0-1.8.4, ClickThroughBlocker 1.12.0-2.1.10.21, ToolbarControl 1.12.0-0.1.9.11
Affected craft, extracted in-flight via Craft Kitchen: Munshot 6 Rover_EXTRACTED.zip
Video of Problem: Video of Rover Autopilot misbehaving

Under Munar gravity, we get weird behavior from the Rover Autopilot module. The Speed Control function seems to work fine most of the time, but the Heading Control function only seems to work while under the Safe Turn Speed (for obvious reasons). What isn't working right, is that the rover doesn't seem to pick up on the idea that it needs to apply either brakes or reverse motor to slow the rover to the point where Heading Control is willing to turn it. If we manually slow the craft, either by forcibly applying brakes or reverse motor, Heading Control kicks in appropriately, but Speed Control fights us all the way, and we end up in a situation where Heading Control has about 2-4 seconds to effect its turn before Speed Control exceeds the Safe Turn Speed. Speed Control does start to slow down when it approaches a Waypoint, but it seems to stop decelerating about 0.1m/s above the Safe Turn Speed, preventing Heading Control from ever kicking in.

Testing on Kerbin has showed that Rover Autopilot works flawlessly, and we're quite happy with it, so it only seems to do this on The Mun.

We tried multiple variations on both Speed PID and Heading PID changes, and neither seemed to have any effect. Interestingly, it seems that this also applies to Heading Control even when no Waypoints have been created, since the Rover Autopilot still uses the same Safe Turn Speed setting regardless.

We're able to provide more information if needed, please ask.