Since the new patch became available, I thought I'd try to finish up some quests etc, I had trouble with during my first playthrough... and found some more problems. As I loaded a earlier save to work towards getting the final achievement I need (One with the Shadows), I've found that some quests I originally completed with that character, I've been unable to do so. Case in point, the Jobs that Delvin Mallory and Vex give you in the Thieves Guild, I can do them... but when it came time to do a 'special job' for Delvin... it had him tell me initially what i had to do etc, yet when I went to Solitude to speak to the NPC in question, the quest didn't trigger. I tried to get some Daedric quests done (Boethiah's Calling, The House of Horrors, A Night to Remember, A Taste of Death and The Mind of Madness) as A: Was bored and B: in the case of Boethiah's Calling, the Ebony Mail would be useful for the Thieves jobs I needed to do)... yet they didn't trigger. I followed the info as it was stated in the Elder Scrolls V wiki... and nothing (I still can't get 'The Forsworn Conspiracy' finished either!).
Now, don't get me wrong, I do like this game... but these glitches! I'm regretting paying out $100 AUSD for this back in November last year!