I realize that this doesn’t answer your question re: failures, but looking at your progression levels chart, it is not a surprise to me that a workout like this, while tough for anyone, might be especially difficult given your PL profile . . .
IF your goal is century riding, then to the extent that your PLs represent progressive Time-in-Zone for each category (I don’t know TR’s algorithm), then the lower zones, including endurance, tempo and sweet spot should be much higher before you spending as much time as your chart seems to be implying in VO2max (and above) type efforts. “If I were you”, I’d go off plan and load up on some more progressive tempo and sweet spot efforts [with endurance in between] before redoing a lengthy LT effort like Nelson.
FWIW: If you look at @mcneese.chad PL profile in the links he provides above (clicking on his TR user name), even though it indicates he is training for BMX, and excepting his lack of time in tempo, his PL profile is more of what I would expect to see from someone nearing the end of a century plan. And perhaps in a bit of irony, based on your PL profile, I wouldn’t be surprised if you would crush an MTB course with 3-8min short steep hills or on a BMX course that Chad seems to be training for.