In my first playthrough of Leliana’s Song (a DLC to Dragon Age Origins), I found what I initially thought to be a bug… I’d looted a Mages Collective Cache for the Find the Mages Cache quest, and died. Upon loading my save, the cache didn’t seem to be clickable anymore.
As it turns out, it wasn’t a bug (although there was zero information about this out there). The locations for the Mages Collective Cache’s have extremely small clickable areas. If you’re doing the quest, go to the location marked with the X and *slowly* move your mouse around all over the area (whether it’s the pile of wood, the bags, etc).
Eventually you should end up mousing over the tiny area and will get the clickable popup. Don’t forget to hit up all the caches – fortunately they’re all marked on your minimap with an X. Once you’ve done them all, the “Find the Mages’ Cache” quest should be complete.