I have experienced at several encounters during m+ that dispel does not dispel. It hits the friendly target, the friendly target is in range, and the dispel activates GCD, yet the debuff is still on the friendly target.
I am running a mouse-over macro on Purify, and I am using Shadowed Unit Frame where the party frame flares up the players with debuffs. Is there any fundamental game mechanic I have missed out on, or has anybody else encountered this?