Thanks for the file, François!
What I have found, the Skeleton had keyframes. The Figure is moving by itself and so the Pivot needs to be stationary.
Only one of the three Motion Clips were connected to the Pivot.
I wouldn’t double the animation with keeping the keyframes, but you might have some reasons for it, so it moves even while there is no Motion Clip.
The Pivot Object is there to add motion, but if the motion is already in the joints, anything else would double it. The Pivot object doesn’t need to be where the character is.
Since the motion in the joints is very detailed already, I would even replace it with a Pivot Object. Only the motion that needs to be added.
Adjustments can be done , as in the third paragraph of the this help-document:
https://help.maxon.net/#OPIVOT
If you don’t like to have for each Motion Clip an extra Pivot Object, there is an option to convert all Motion Clips into one Motion Source. I would not recommend it, though, but I like to mention the idea.
To use always the same Pivot Object for all Motion Clips might fail, especially in the areas where these animation are blend together. That might be tricky.
Again, the animation in the “joints/rig” is very detailed, I would add only needed movement with a Pivot Object, but not relate the complete animation of it, in other words, here in this example it should be the adjustment, to align the three different poses, and support instead of taking over.
I hope that helps a little bit.
All the best