It's your fixer. Your film should also be clear, not purple. Tmax films tend to use up your fix faster than just films. Mix up a fresh batch, and run the film through it again to clear the dyes, and hopefully the yellow.
My experience as well. It is a while since I used Tmax as it just became too expensive but if I recall it needed at least two soaks. The first soak say 1 -2 mins with agitation removed most and the second soak for 3 mins removed the rest.