Materia melding failing 21 times in a row

[Inquisitor]

It said 35% chance to success but failing 21 times in a row is almost impossible.

Something that is ALMOST impossible can still happen. It's very unlikely that this would happen to any particular person, BUT when you consider the entire population it's almost inevitable that this sort of thing will happen to SOMEONE. You basically "won" the anti-lottery. The odds of being a big winner on power ball is much lower than your situation, but some lucky few still manage to win it.