An object cannot be inserted below itself

What causes this issue?

You have attempted to place an object within a hierarchy in a subtree
located below the previous position of the object.
Since this would lead to a state of inconsistency (the subtree would no
longer be connected to the rest of the hierarchy), this operation is
not allowed.

System Response

The attempted rearrangement has been terminated.

How to fix this error?

Try to rearrange the objects in a different order in order to achieve
the desired hierarchy.

Error message extract from SAP system. Copyright SAP SE.