Hi Dave, I notice you were participating in another thread that I believe is related, though didn’t see any input after the cause was determined. can you have a look at the whole thread for Layout 2021 - Viewport Issue - #38 by adam and compare it to this one
Your advice to Pjs is very good, though I believe misses the main point of what is happening with random sections being turned on during export to PDF, which I believe is a very major layout bug.