I had the same.
To show the "?", simply open your quest log (L), and click on the yellow circle at the front of the quest name to hide it from your screen, and then click on it again to make it reappear.
And there you go, "?" has appeared!
Or for an even easier method, disable Carbonite's function to move tracked achievements into the Quest Watch window. This stops Carbonite from suppressing the Objectives window, which is where Blizzard shows the "Click to complete" box.