Sometimes in motion capture and character animation, keyframe handles & values for animation holds are not perfectly flat. This creates an undesirable sliding effect. By running “Flatten Holds,” it will flatten the hold keyframes in the selected F-Curves/Keyframes.
Redo Panel
Target
Flatten Holds’ target: either the Selected F-Curves or Selected Keyframes
Threshold
Threshold for difference in keyframes. Increase the value to see more holds.