Twice I have selected the correct answers for Grace of Dawn in the Mysteries of the Raven Sanctum achievement and have not received credit.
I've only done it once, as I was cycling through all the variations to get the achieve. But per my notes, Grace of Dawn comes from driving off the wolves, saving the history book, and letting the prince die.
Things for you to check: You used the above answers. You didn't still have the raven buff on you from a previous attempt (which I think would stop you getting the option to answer the questions at all). You were on a character that has completed the story (which I think you must be on or you can't even get inside).
I'll go try for Grace of Dawn now since I have an alt available to do it, and report back here.
Reporting back, that worked. You said you weren't getting credit. Do you mean the achieve isn't checking off that you have done Grace of Dawn? Do you have a screenshot showing the Grace of Dawn buff active on your bar but not checked off in the achieve panel?
Yes, the achieve isn't checking of Grace of Dawn for some reason. No screen shot but I will next attempt.