There's a problem with the cooldown timer for Quickslot consumables. As has been reported in various other threads, you are often unable to quaff a potion from your Quickslots and the game will play the 'unavailable' sound even though there is nothing that should prevent you from using it.
Today, I found it this is not just for Potions. While trying to repair a keep, I ran into exactly the same problem. Spam Q to use a Repair Kit from the Quickslot wheel, but the game plays the 'unavailable' sound for well over 10 seconds.
While not being able to use a Repair Kit is nowhere near as dangerous as being unable to quaff a Potion, it does seem to be one and the same problem.
Edited by Lava_Croft on April 11, 2015 5:50PM