Two things. (And yes, i am writing up the build app as i type this one.)
One: I find it a waste to carry torches while mining so i generally ALWAYS mine at light 0. I play with a bright level.
Second: Most of that time, I wasn't using X-ray, technically not at all as it was TP and as you have plugins against that how would i have been able to see the iron you spoke of? I found a place where mining hadn't occurred and saw a ravine in the distance. Turned off. (Before the pictures you sent most of it was pretty straight except for wherever i found dirt/gravel because they are a pain to dig through, i often change direction around them). Was curious as to where it was after, so i logged out, turned it back on, found the ravine, headed towards the gold not because there was gold there, but because its hard to tell where the cave cuts out.
Believe me if you will or won't, not agreeing with the facts there is just being ignorant.