I think you need to get close to the corpse to get the process started, when it looks like it's disintegrating. After that then you can move away. I remember during the weekend that I had to chase a dragon's corpse down the side of a mountain to get the soul. Or it might be that the process doesn't start until the corpse has stopped moving.
As for the not absorbing part, I think that bug was fixed in the 1.2 patch. Haven't had any recently.




