I seem to be the same problem. In my journal, under "The Undead Scourge" questline it says i faced and defeted youknowwho, who dropped a youknowwhat and that I should report back to Aureus. Under the "The Skeleton King's Summoner" it says I have discovered who resurrected youknowwhoand that Arhu will want to know what we have discovered.
However when I go to speak to two of them, none of the dialog options indicate anything to do with my completions of the aforementioned quest
please help. I apologize for my poor attempt at spoiler coverup.
EDIT: Nevermind, after I shutdown the game for a break and came back the dialog options worked, weird