Hi,
Just tested here with a CC3D, works fine.
PWM input: connect the first connector (usually the one with 3pins, black/red/white) to the PWM receiver
Hardware tab, Sbus (mainport) and PWM to the receiverport
Remember every change in hardware tab need a reboot, remove usb and external power and connect again.
Finally you can run the transmitter wizard or redo a manual calibration if input type / channel are already affected.