Today we were doing vRPB vet Red Petal Bastion and got a rage quit tank right when entering instance, then another one joins right before and rage quit right after we defeat the 1st boss. So I summoned out my Zerith Var that is built as a tank with the stab as the taunt.

However, during the 2nd and last main boss fight, the bosses aren't taunted even after I saw clearly that he stabbed them. They instead went for the rest of us. From the debuff list of the boss there's also no icon of being taunted.

I have heard for long that there was the taunt bug on Gothmaul in IA but have never encountered similar bugs elsewhere. Has anyone else been experiencing such things in other encounters as well?