Engine Audio Pitch Fluctuates When Rotating in Air

[JustInvoke]

The pitch of the engine audio of a vehicle is lower when moving backwards through the air compared to when moving forward. This is most noticeable when stunt mode is enabled in the demo scene and you rotate laterally in the air while holding the throttle.

This issue is present on both gearbox and continuous transmission types, but disappears when auto shifting is disabled on the gearbox type. This leads me to believe it is related to the transmission classes, but I haven't been able to find the source of the problem.