Editing values of a control rig can cause the undo to stop working in Anim Details or Sequencer

It has been observed that the the undo function may stop working after the User changes values of a control rig with the slider in the Sequencer. While using the slider, the value stops chaning after half a second and the "Can't undo while "X" is in progress" is displayed in Edit Menu. 

The issue, so far, happened when:

• setting key values in Sequencer
• changing property values in Anim Details

There is a workaround: user needs to clear the undo history, but the issue may reappear while changing  values again. 

1. Open a Level Sequence
2. Select any control rig
3. Create a key
4. Edit a value with slider

Actual Result: The slider stops after half a second and the User is unable to undo changes. 

Expected Result: The User is able to change any value with the slider without issues and the undo function cannot be broken.