Textures not loading?

I’m following along with the video/instructor and every thing is going fine until 16:40. When he starts to paint over the base texture with another texture, it takes a second to load, briefly replacing them with a large square of the default grid pattern before loading. However they’re never loading for me, when I try to paint with the new textures, they are replaced with a large square of default grid that never loads the texture. Am I doing something wrong???

Edit: Sorry, I’m new here. The course in question is Unreal Environment Design, and the lesson is Quixel Bridge Materials.