For some reason certain walls do not display in my drawing. I can see them in the 3D model and they are included in the drawing's clip volume, but they do not display in the 2D drawing model even though other walls (of the same type) do display.
The "problem" walls in this case were accidentally placed as Construction Class elements in the 3D model. And because the Constructions option is disabled by default in the drawing's Reference Presentation dialog these particular walls did not display. To resolve this issue you can perform either of the following steps:
1. Open the drawing and enable Constructions in the Reference Presentation dialog.
2. Change the walls themselves to Primary class in the 3D model using the Change Element Attributes tool.