The geometrical link between the plane and the face
is no longer maintained. This means that the face is no longer
recognized as the reference used to create the plane, and therefore,
you can no longer edit the offset value.
The way the plane was created is ignored. You can
check this by double-clicking the plane: the Plane Definition dialog
box that appears indicates that the plane is of the explicit type.
In the specification tree, the application indicates
isolated elements via a red symbol in front of the geometrical