I'm not sure if it's supposed to get dispelled, but if so: Turn this into a feedback thread as it would be nice to make it immune against dispel since the skill has a fairly high cooldown. If it's not supposed to get dispelled: The skill remains active in the upperright corner, however, the attack buff is nullified. I haven't tested if the skill mp reduction also stops working.
Can confirm the mp loss does not get dispelled, only attack buff does. As to whether or not this is a bug, I think it depends on if infinity is also unaffected, because if so, this behavior seems intentional.