I shall not double-post this but relates heavily to the DVDAPro 6.0 release and has been discussed several times in this forum as well.
Problem:Vegas 12Pro all-builds have an encoding color-shift bug when used to produce video streams for Blu-ray discs thru DVD Architect Version 6.0 application. This has now been verified by SONY as of March 16, 2013 - and their statement as of this date "to be dealt with and resolved in future release".
As far as I know if you produce streams with any prior version of VegasPro and use DVDAPro version 5.2 or earlier, you will not have the pronounced and very undesirable color shift.