I am not an amateur but perhaps I've made an amateur mistake somewhere. I doubt it after 20+ years of developing my own film but I am indeed willing to admit a mistake if I made one.

This image below was developed using (fresh) Xtol stock and fresh fixer developed for just under 10m wth a 2m pre-soak at about 8C. This is (new, unexpired) Tri-X 400 @ 1600 shot with a Nikon FE2 (and vacillating between a 28mm, 55mm and 300mm fixed lenses). I shot a roll just before this one (c41 @ 800) that came out fine. This one, clearly, did not.

I am truly surprised this happened and am trying to pinpoint where the problem originated. The film back did not get opened during the roll (and fwiw the film was loaded in 'subdued' light). What also surprised me about this fogging is that although the (entire) roll was fogged one way or another, certain images came out that were in between completely fogged images (e.g. no image).

Clearly we're seeing light leaks through the sprockets...

One thing I know for sure- the light leak is not a result of lens switching (e.g. light sneaking in through the lens opening from a torn curtain or whatever)...

Any thoughts?