So I was painting textures on my landscape when suddenly specific textures would remove all textures on the component it was applied to.
Are you sure it is not just loading the new texture, sometimes it might take a while depending on the texture or mesh
You cannot use more than 4 painted layers in a landscape component (quad section) by default due to the limitations of the directx 10 shader model, whenever you paint more than 4 layers onto any single component in the landscape that component will glitch out. Unless you set all of your textures to use Sample Source → Shared Wrap which will then allow the material to use the new directx 11 shader model overriding the limitations of the older shader model.