I've noticed this issue since day one, but have never gotten around to reporting it until now (because of all the new "hide helmet" options).
When I created my Exo I opted for a red primary (body), yellow secondary (head marking, ears) and the "7 barcode icon" that's available as a head marking. As pictured above (cutscenes appear correctly)
[i]The bug is during game play (tower, reef, character select, and character preview) the yellow does not appear on my forehead (which makes the "7 barcode icon" hard to see).[/i]
Image here (I only know how to link one): http://i.imgur.com/plUcmqe.jpg
This has always been the case, and only now with all the helmet-less-ness has it motivated me to post.
Hopefully it can be resolved.
Regards,
The7thLegion