I reinstalled, and got the update working. It fixes awful PC bugs like not being able to equip spells in specific hands properly, and not being able to examine/rotate items in the inventory menu.
BUT it adds new bugs, like not being able to cancel the lockpicking minigame, and certain popup dialogs, like the "are you sure you want to be this character" one at the beginning of the game won't let you choose "yes" OR "no," regardless of what key you press, or where you click with the mouse. I only managed to get through by loading a new game and switching to my XBox controller.
Jesus fucking Christ, Bethesda, get your shit together.