on my latest model I encountered a problem with the interpolation of the pelvis position (at least I guess this is what is happening) in Blend Spaces and State Machines.
I am having the same issue with the default mannequin rig.
Some thread mention the issue is caused by mixing new animation to imported anim like maximo, so i don’t know about you, but in my case, it is not the cause if the issue.
i can reproduce the issue simply by opening a new scene, loading the default mannequin, creating 2 poses in it, export, link it into a 1D blendspace and my feet will move through the ground similar to this.
I played with the anim compression, i tried creating a “mid” pose to help it blend, but it’s still happen.