I personally don’t have any issues with him using “defpoints” for a viewport layer, but with that said I do have a designated layer specifically for viewports.
But, back to the issue at hand. I would check to see what layer the x-ref’s are on and see if they are on the defpoint layer or any...
I have used PDF995 (www.pdf995.com) for many years and it has served me well. (Free version available but for $10 you can get rid of the popup.)
I made page setups for the offices (for the standard page sizes) so it is easy to make every pdf the same and use the same plot style. (We use stb’s...