DRV8308 EVM - speed control

I'm using DRV8308EVM with GUIComposer (DRV8308EMV_GUI v1.1) in combination with a 3-phase BLDC motor (1 magnetic pole pair)

The "PWM Modes" works all fine. In the "Clock Frequency Mode" I'm able to start but the clock freq has no effect to the speed. Changing LOOPGAIN or SPDGAIN without any impact.

Any ideas I could check?

thanks, gmlo