UpdateAfterGeometryEdit should be called after editing the UDynamicMesh owned by the Selector (TargetMesh). This may be an external DynamicMesh in the case of a DynamicMeshComponent, or a temporary UDynamicMesh in the case of (eg) the StaticMeshSelector and VolumeSelector subclasses. In DynamicMeshSelector the MeshChange can just be emitted as a transaction, this is the default behavior. However in StaticMeshSelector, the StaticMesh needs to be synchronized with the UDynamicMesh modification in the same transaction. And potentially the MeshChange does not need to be emitted at all in that case.