Hi jason,
Please look at the file below. I took a Mixamo T-Pose (Frame 0) and retargeted it to a Character-Mixamo object. I didn’t change any weighting, just auto, but the rig transfers the movements.
https://www.dropbox.com/s/j5g5ac2oh3x3v0a/CV3_2023_drs_22_CAmr_01.c4d.zip?dl=0
I know that some instructors suggest placing the Motion System at the hips. I keep it with a Parent Null for various reasons. The Hierarchy is crucial for the Motion System.
What I found in your file was a selection of things. The weighting seems very simplified. The Hips move a lot. When you rotate the Spline, it instantly becomes obvious (For that exploration, I deleted the Motion/Mixamo part to see the Character set up first.
The two Rigs are not well aligned. When you look at both simultaneously, the differences are apparent. The joints point in a different direction between the hip and upper leg.
The Retargeting area (Click on the Spine Hips_Con+) has no entry for the Hips from the Mixamo. In the example above, those entries are grayed out. In the file I got (above), they are not grayed out and are exchangeable.
I’m not clear how the file from above got into the stat it is. Hence, I have set up a new one to see if something in 2023 is broken. But it works.
Please try with Jonas Pilz’s exact instructions in Maxon Quick Tip 261. Perhaps start with both Rigs freshly. Perhaps check with a Mixamo T-Pose first.
https://www.youtube.com/watch?v=HS2S5SleiHE
Perhaps give this a try as well
https://youtu.be/z93e5_7P54g
All the best