Very weird. Just had this problem with a roll of Tmax 100 I developed on a steel reel yesterday. Although it showed uneven kind of mottled development all over it certainly had a pronounced over development on the edges. I struggled to get the roll on a 120 patterson reel and failed. I don't know if it was too humid in the changing bag or what. So I abandoned the Paterson reel and loaded the thing onto the steel reel. The problem with the steel tank is it takes longer to pour stuff in because it air locks if you are too aggressive. So developer and stop went in slow. The negative was a total write off. I was using pretty fresh stop and freshly mixed rapid fixer. The Xtol is a few months old but it beautifully developed a tmax 100 negative a week ago. I agitated pretty aggressively once a minute. 30 seconds initial agitation once the developer was in. Strange.