Need advice on (Per Bone-) Motion Blur

I am trying to figure out how to activate (or increase the effect of) object and per-bone motion blur.

I did find the setting for per-bone (and activated it), but without any effect.
Not even wohle objects moving around show any motion blur.

The only thing I managed to do so far is increasing the motion blur effect in the camera settings.
But that is not what I want. In fact the camera movement should not have any motion blur applied to it.

I obviously did miss something, since this seems pretty basic.
Could someone please point me in the right direction? Thanks!