So I have a clean install of Skyrim with both Dawnguard and Hearthfire and I got to Harkon and accepted his offer. So he bites me. Fade to black. Then the usual and I see my guy and Harkon and we do our chat thing and he tells me to change.
Sure, buddy, I'll assume the mantle of the vampire lord, let me just dig that out of my pack, okay?
Trigger the power.
My guy hunches over and little blood chunks fly as usual but there is no change. The character just stays there. Hunched over. Not changing. Occasional blood effects spraying out. Harkon repeating himself. No inventory access. Can't move.
I'm putting this here not because I expect a solution. I don't. I'm putting this here in case Bethesda is still looking at this board. Maybe they'll see it. Or maybe somebody has had this problem and was able to fix it. But after my little search of the boards, I didn't see anybody else with the same problem so likely this is absolutely futile and I'll just continue to hate this version of the game.
Dammit.