Rare Steal always fail?

Stealing Brachosaur ribbon is 1/8 chance, but sometime especially in the coliseum, no matter how long it take (fast forward button help a lots), I can never steal it. Why is that? I don't think it just dumb luck, bec fast forward a very long time using Gau max Def+ MeritA+ Thief Knife+ Offering.

If the rare steal formula is very rigged, then is there a patch that can fix this?

Later:
Ah! I think I discover why it failed. I think using a rage that use Special Attack status that Brachosaur is immune to, will always fail. Either this is a glitch, or the quote "Couldn't steal!!" just mislead me. Otherwise, something is rigged that a simple Lobo Rage sometime failed to steal.