Batisse S2 bugged?

I just got a Batisse so I thought I might try it out in W11. Had his S2 maxed out and gave him enough gear (65% effectiveness) so his effectiveness should be enough.

However, when running him, I found that his S2 seems to miss more often than it should be. I have counted all his turns in 7 runs. He had 34 total turns against wyvern and only successfully applied attack down in 6 in those turns, which is < 20% of chance to apply S2's debuff. Does anyone else running him see the same issue?

(Also, can SG please change his auto AI so that he prioritizes targets that have attack down debuffs?)