...The node is no longer at the location that it was moved to.

Or...

...The node no longer exists in the mesh.

Node movements listed in the Worksheet can become obsolete if you implement mesh changes such as Mesh Numbering, Fracture, Mesh Connections, etc. Undo actions are not available once a node movement has become obsolete.

To return to a base mesh, you need to remove your mesh changes in the reverse order of their implementation. If this is not possible, you may need to clean and re-mesh your model.