I've gotten this quest marker pointing towards a cleared dungeon, which after researching I found out is actually a dead end, because of a bug. Is there anything I can do? Is changing the quest location a possibility? [I'm on the PS3, by the way].

Load a save from before you got the quest and try it again. It may point to a different dungeon.

Also, it may take some time for an enemy to spawn in a radiant assigned dungeon.

i have found that the dungeons seem to be random.

so do as CCNA advised and you should be golden.