Control Rig - Undo doesn't function correctly with proxy and multi bone controls

Issue from my Technical Animator where the undo operation in Control Rig doesn't work as expected on Proxy Controls. He has recreated the issue using the "Control Rig Samples Pack" and recorded a video for me, which I have attached.

Steps to Reproduce

Steps to create issue:

1. Create a fresh 5.6 project and add Unreal's standard 'Control Rig Samples Pack'

2. Load CR_Mannequin_Body and zoom into the left hand

3. Rotate a control that mapped to just one bone (thumb_03_l_ctrl) and note that undo (via hotkey or menu) works as expected

4. Compile to reset test

5. Rotate a green proxy control such as index_curl_l_ctrl and undo

6. Rotate the same control again and notice the bones involved get crushed together

7. Compile to reset test

8. Rotate a blue control that affects multiple bones like pinky_01_l_ctrl

9. Now rotate a single bone control like thumb_03_l_ctrl and undo

10. Notice that some of the digits of the pinky_01_l_ctrl change have been undone.