My solution to this problem is to dunk and shake the film in the fixer for another five minutes if I have this magenta coloring after the regular wash. Yes, you can re-fix a film again and again; in the case of Delta and T-Max it works wonders when I have some residual magenta after the usual 7 to 10 minutes fix. I have been told by Koday and somebody with Ilford that these "new generation" films work somewhat differently than the old ones.(posted 9631 days ago)I know you are not asking for advice beyond the one you asked, but have you considered using Agfa film? It does not have this problem and it gives far superior images...try it, you may like it!
Bye - John the Fisheye