Mike, I cannot guess what Tetenal added to their blix to make it work well with color films. I know how hard it is to do the job right on color films with a blix. Therefore it would be useless for other than a Tetenal chemist to advise you on this. IMO anyone else would be blowing smoke at you.

Dyes can be destroyed by oxidants, reductants, metals, and pH changes.

You cannot overdo the Kodak or Fuji Bleach or Fix solutions unless you use very very long times. They go to completion with chemistry designed for the dyes.