Reallusion, you're trying to kill me.
Movement of the hip bone is somehow broken in 7.3 which means that aligning motion clips won't work if there's any root bone movement in the animation.
Notice the character's wobblyness once he's moved by the hip bone. (Box is linked to his root bone to help show the movement)
So I'm seeing these features not working properly as a result:
Moving the root bone in "edit motion layer"
Animation clip alignment
"Reset to default" pose function in edit motion layer.
If anyone is experiencing this please give a vote on the feedback tracker bug linked below.
If it's not happening to you (on clips with root bone motion), let me know too.
https://www.reallusion.com/FeedBackTracker/Issue/Moving-a-character-s-root-bone-now-results-in-broken-animation