Contains story spoilers!
From the moment on Valeria is supposed to follow you in Act 2 she is somehow invisible/stuck below the ground(?) in my game. You can hear her talk and partly see an effect where she's supposed to be but she's never actually visible and consequently she's also not visible in all cutscenes thereafter.

This is mildly annoying for a while but it becomes gamebreaking when fighting Hemlock after he's blocking you path and you're down in the pit. After the fight you're supposed to talk to Valeria. As she's invisible and somehow below ground it is impossible to click on her as only the yellow marker is visible where she's supposed to be. Hence you're stuck and can't proceed with the game. Reloading and playing the part again unfortunately does not change anything about that as she'll just be invisible again.

Can't finish the game because of that :(