Kodak's data sheet suggests if there is a magenta cast to the negatives, they may not have been completely fixed. A slight cast can be removed with hypo clearing agent, but a heavier cast requires re- fixing.(posted 8383 days ago)Since you say it is purplish/blue, I'm not sure if this is what you are seeing, or if it is the anti-halation dye/coating, but I'd try re- fixing in fresh fixer followed by HCA.
If this was the last roll you processed using the same batch of fixer, it is probably incomplete fixing. TMax films exhaust fixer faster than traditional emulsions. Try soaking in distilled water