There's a really annoying bug with the client as of the latest update. Sometimes when you try to chain multiple abilities, in quick succession, the first ability won't trigger.
For example, let's say I quickly click chain attack I and then critical strike. Now, the first attack should happen and the second should be queued, but what actually happens is that the icon for the first ability greys out, the ability doesn't trigger, and then the second ability is used. The first ability then stays greyed out for 30 seconds plus. This is REALLY annoying when it happens with an ability that's supposed to have a short cooldown, such as gold rage. It effectively stops you from using the ability because you can't click on something that's greyed out, even though the ability (as far as the server is concerned, at least) is ready for use.