I'm at the part where I run into the four Thalmor soldiers. I'm assuming one of them has the key into the abandoned house? Well, every time I kill them their bodies freeze in midair as if they are "planking" (lol), and I am unable to loot their bodies for said key.

Anyone have a suggestion?

I can conferm that one does have a key, although idk what to do about it.

You could try calm or ice form shout and then pickpocket or have a follower kill them and see if it still happens