Good Morning Lloyd! Most likely it’s just the camera view.
Click on one of the Construction Plan – Heavy scenes, then do a zoom extents… Do you see the walls? If yes, you can either update the camera view on all of your Construction Plan scenes… Or, just stretch the viewports around in LayOut until you find your drawing. You can drag them in even though they appear to be blank… Your drawings are floating somewhere in there…
If not, is the section plane cutting below your model and hiding everything?
Also, 99% of missing geometry is cause by mis-layering. Is everything on the right layer/tag?