How to export a wall having an Opening in it from DGN to DWG?
1. Go to Level Display and then change the 'View Display' to "Global Freeze" and turn off the corresponding symbology of the Opening "G-ANNO_NPLT & G_ANNO".
2. Go to File>Export>Common File Types>DWG. Select "Options".
3. "Save as DWG/DXF Options" dialogue box appears. Expand "Entity Mapping" and also expand "3D Unfilled Elements". Select "5 or more sided Polygons" and change the Value to "Polyface Mesh"
4. Click on "OK" and save in proper location.