In order to track position in relative space, Perception Neuron needs an origin point of contact and a follow through.
Sliding does not does register as a foot contact when you analyze the movement. Perception Neuron captures position in relative space based on foot contact.
In order not to get too technical, our IMU sensors uses a predictive algorithm to anticipate a foot contact based on the impact of the foot and the location of the ground. When you have a performer slide their feet, Perception Neuron will not understand position in world space because there is no anticipation of contact.