Why are my Characters not following the slope correctly

Ground adaptation is made to follow a ground that differs from the one the animation was made on, but when the slope's gradient is too high, it reaches its limits.

The limit is in fact a parameter in the Ground Adaptation behavior: the character won't put a step higher/lower than the current step's height +/- % of the limb's length.

This is configured in the advanced attribute of the Ground Adaptation Behavior: