Thanks, Uwe. I agree — the problem seems deep in the PDF export code. Ugh...
Yes, with this printer, I have chatted to them about it and they were horrified! Unfortunately, they use X-4 for very specific reasons based on how their presses are set up. I'm trying to come up with a temporary fix with them while a more holistic solution is developed, in the longer-term.
Do you have any suggestions on how I can get this issue under the nose of the right people at Adobe?
Thanks again.