Volume element Group on geometry not working correctly

I created a box and then partitioned it in half. I created a group of each half in geometry. After meshing I normally group on geometry to get a group of each half, but it is not working correctly in this model.

if you check ** Consider Shared and Internal Faces and rerun the mesher, the two requested groups are created. Please see the Help menu of the algorithm for additional information.

Awesome big help thanks