What do you have in "Ports and pins - Output signals" and "Ports and pins - Spindle setup"? Try this:
Output signals:
- Output #1 enabled, port 1, pin 17.
Spindle setup:
- "Use spindle motor output" checked
- "PWM control" checked
- "Disable spindle relays" unchecked
- "Clockwise M3" output #1