Yep, this is something that is not very well done in the presets, but is easy to solve.
Just lower the dynamic range (1th parameter of the quick controls) to somthing around zero.
This way you get full usage of the expression control that is standard assigned to the modulation wheel.
What you hear is the accumulation of the two controllers, and it leads to an almost inaudible sound when both are used at the same time. Once you reduce the dynamic range, you will notice that the soundbank is in fact well build with lots of multilayerd samples.
kind regards,
R.