Hi, I'm finding that the 'right click > Sample Hip to Root (XYZ)' is adding unwanted (and incorrect) Z offset to the root bone. Any tips?

Sample Hip to Root (XY) is the default value when applying motion (active auto align position), the setting is good for most cases in which action is on the ground. if the motion with Z movement, like go upstairs, it's better to use Sample Hip to Root (XYZ) for futrure motion alignment.

Thanks, to be clear - I am using XYZ. The problem is IClone is incorrectly setting the root bone position in the Z axis (as shown in the images). It is placing it below the floor.

the algorithm for XYZ refers to the height between the Hip and Toe from actors T-pose, if the actor performs a squat pose, the Z position will be underground like the picture you share.

Thanks, I appreciate your help. I now understand what IClone is doing (placing the root bone in Z space by a set number based on rig T-Pose), but I don't see how this would ever give useful results. Any animation will have hip Z movement relative to root Z movement. Therefore, the root will always being going under the 'floor' by amounts dependent on the animation. This will create inconsistent Z locations on the root bone and will not work with systems requiring proper root motion (such as Unreal Engine). 

Assuming there must be a method for correcting for this, I thought IClone may use the first frame for reference. I tried merging the character's default T-pose as the 1st frame of my animation clip, but this did not work. The 1st frame of the animation has a correct root Z position (as expected), but as soon as the character starts running (my animation is a run to vault), the root bone is pushed under the floor. 

Does my issue make sense to you? Are there any known methods to correct for this?