Control rig bends the knees of my mocap MH animations

Summary

Adding a control rig to an animated MH in level sequencer bends the knees but leaves everything else alone.

What Type of Bug are you experiencing?

Animation

Steps to Reproduce

Using UE 5.6, capturing mocap with Vive Mocap Kit, importing the MH into level sequence. Adding my mocap animation to the MH’s body. All looks well.
Then either I bake to CR or add a control rig to the body, and either way the knees bend. Here are the before and after photos.
Have not found anyone else with this problem online. It ruins every animation. I can lower the foot IKs but it still looks very wrong. Have played with the retargeting in the skeleton without any effect. Happens to all 100 of my characters, so not specific to a particular MH.

Expected Result

Control rig should be applied without deforming my character

Observed Result

Knees bent (and maybe legs elongated a little so feet stay put)

Affects Versions

5.6

Platform(s)

Windows

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