Layout PDF: Unwanted Black Background Appearing in Printout = Catastrophic Failure (Mac Related?)

So, I am being threatened with a workflow reversion back to Revit if this cannot be addressed successfully…

On the left are PDFs generated in Layout on a PC printed from a Mac, on the right are the same PDFs printed from the PC that generated the PDFs in Layout

This is not an isolated event, PDFs printed on Mac’s across the world (both in New Zealand and North America) are producing the same problem…

What is going on here?

Tried multiple fixes, plotting with “Print Paper Color” both on and off in Document Setup, creating a “Failsafe” white filled rectangle beneath all other layers, modifying export settings to either use or not use JPEG compression (and the varying quality levels), not using Layout Layering in the generated PDFs… none of which solved the issue…

can you add the pdf for inspection on my mac…

john