Last time I looked, Kodak didn't recommend that you base fixing on a multiple of clearing time. Instead, they suggest 3-5 minutes in Kodak rapid fixer. Your 2 minutes sounds like far too little.(posted 9171 days ago)This might be because t-grain films do indeed 'clear' in a strange way. I have suggested a mutiple of three times the clearing time, and I do mean a total clear (including colour).
In practice, I always fix for 10 minutes. This may be overkill, but I believe it is harmless. If a t-grain film takes 3 minutes or more to totally clear, it is time to discard the fixer.