Surprisingly, there is almost no literature on the fix for this quest so that people can actually do it, so I'm hoping by posting here this will help some people in getting this quest done while we wait for the proper fix to arrive. The Siege of Cradlecrush is a quest in the Eastmarch zone. The glitch in question occurs when your quest objective is to Talk to the Giant.

The goal is to properly get kicked by the giant into the water to the west of him, over the rocks. It took me about 20 tries to do this. Some tries teleported me straight into the water and the quest didn't advance. Some tries he didn't kick me far enough, some tries I just teleported right back to him after a very brief loading screen. To get this to work, as soon as you're finished talking to him you have run right towards him. I'm not entirely sure whether or not your back needs to be facing the low-point in between the rocks that you have to fly through once he kicks you, but I was when I finally got it to work.

But it's that simple, just run towards the giant and eventually you will be able to get this to work.