Is anyone having issues with the PANTONE Plus Color Bridge Coated Process (CP) colors not overprinting in Illustrator?
I'm using Adobe CC 2018 Illustrator on an iMac. 
Screenshot of the flag's blue field colored with PMS 287 C shows the overprint on the stripes like it should.

Screenshot of the flag's blue field colored with PMS 287 CP does not show the overprint.

This is a CMYK process job and I need to use the colors from the CP book. When I RIP the file it does not overprint even though the element is set to overprint. Overprint preview is ON as well as the element is checked to overprint. What am I missing? Has anyone experienced this before and is there a fix? Please help.
Thanks in advance,
Rob Baker
