Can't Edit Kayframes in Record Mode

I'm using a mocap animation on a humanoid model, and the start position is WAY off center, and even facing the wrong direction. I feel like I should be able to correct t$$anonymous$$s in record mode, but I can't.

I fix the issue by editing the keyframes, but when I try to play the animation it immediately reverts back to the original position, no matter w$$anonymous$$ch part I try to edit. It creates no new keyframe, and does not update the properties. I've even tried forcing a keyframe, and it just ignores it. I have even tried adding new properties to edit THOSE directly, but the animator refuses to make new keyframes when I make edits.

How do I force the edit to stick? I'm not in preview mode, I'm in record. I'm not sure if there is some master key telling the others to revert back, or if t$$anonymous$$s particular type of animation is not editable, but it is quite a nuisance.

EDIT: The animation is not in (read only) format, I actually made a copy of the animation so that I was sure I enabled read-write functionality.

I can add an animated gif demonstrating what I'm talking about if necessary.