I died last night because I got this problem. It was just STUCK! If it's engaged! Attack!
Anyways, I found a work around...
Stuck on attack mode but your character is not attacking?
Re-Target. (Esc from your current target (fully, must not be targeting anything), and target the same one again, then attack).
So far this works for me.
Anyone else have a work around?
Hana Kimi (Wutai) Miqo'Te of Gridania Pug/Weav/Gold/Leath