I've run into this a couple of times now.
The first time I noticed it was when I had created some custom light fixtures and forgotten to put a void into the family to cut the ceiling. The fixtures would show up fine on my screen without a void cut but when I would go to print they wouldn't show up on the printed page or .pdf. Adding the void to the family fixed this.
Now i'm running into this again with a linked mechanical model which has some diffusers and returns that are coplanar to the ceiling and they look fine on the screen but don't print. Am I missing some way to get the linked model to cut the ceiling and therefore display properly? Or do I have to go through and place diffusers into the architectural model?