What's wrong with the manor? I get the robes, I get the passphrase, but I never get the option of telling it to the imps? 

 

My Journal indicates that I've done everything I need to do, including looking through Fassina's Diary.

 

I also couldn't pull that off. I could be wrong, but I think you need super high levels of bluff.

I just did this with the robe and passcode and it worked. I don’t recall it doing a skill check, I just used the LIE option when talking to the third yellow eye imp. I do know that if you killed any golems or imps it triggers an alarm and you lose the option to disguise yourself.

 

I entered the manor from the shop next door using window and grapple across avoiding the front door.

It was a bug. It's fixed in the beta branch.