Models are invisible save for their outline

So a couple of friends and I are working on a game together, using Unity Collab. For one of them none of the models show up, even the file icon is just a black square. It happens to all models, including the primitive shapes from Unity and only in this project, other projects with the same Unity version are completely fine for him.

Image: https://imgur.com/a/JLVl70i (Sorry this isn't a screenshot, I didn't take it.)

We're using Unity 2019.3.13f1