Seems like a colour management policy problem. Are you assuming a "safe" CMYK and then in some stage of your workflow invoking colour management?
Leonard can correct me if I'm wrong but if you do not use a PDFx then the device profile is assumed to be the profile in the color management preferences. If the profiles are the same in colour management and in the target profile then your black is kept pure.
This is one of the reasons for always using PDFx1a or PDFx4 for print ready files. (They have a specified output intent)
Learning by teaching!
Given that the VAST MAJORITY of Acrobat users on the Mac obtain their copies as part of the entire Creative Suite, we honestly haven't seen the need to create a demo for the Mac.
Originally Posted by Stephen Marsh
Of course, you never know what the future may bring...