Math Expression Name cannot be changed alone

The title is somewhat confusing, but I didn’t know how to rephrase it.
Well, Math Expressions have a Name and an Expression within their Details Tab.
However, Changing the Name, changes the Expression and vice versa. So my Math Expression should be called “XYZ”, but then my Expression returns “XYZ” only although I have a much more complex Math expression entered earlier.


After I change the Name:
(not correct!,Expression should stay as it is)