If in an element that is below a hierarchy, we apply a free scale distortion in
camera view with transform tool, and the properties of the layers of nested
elements are established as separate scales, the element may be rotated with the transform tool without distortion at any angle, but, if we use IK tool, to rotate the element, there will be a distortion proportional to the angle of rotation.
To avoid these scale deformations using IK tool, is necessary to block the
scales in the next higher element in the hierarchy. Now, you can apply a free
transformation to the child and rotate them with the IK tool without problems.
Yoryo