Strange RGB spot colours appearing when 'publishing to PDF'?

I've asked a similar question in the past but still experience the same problems when converting files to PDF.


The 'mast head' is a monotone bitmap filled with PANTONE 032. When I attempt to create a pdf using the settings above (convert all colours to greyscale and leave spot colours alone) I get the rather strange appearance of the PDF with the unusal spot plates of Blue, Green and Red?

I need to create 2 plates ultimately as these magazines are printed in black only with spot colour (032) on the front page only and I'm struggling with the results I'm getting.

Any ideas?

Cheers in advance