At first, I thought CC was just borked, but upon removing my joystick assignments to Gas, it worked.

Hrm, that makes sense, as the vehicle is setting the throttle to one position, and the JS is setting it to another. Still, I should be able to fix that. Only issue is getting it working so you can still press the gas with CC on, but not drop below the CC speed.

Fixed in V18.5.0.