I'm working on a new project (Unity 2019.2.4f1, HDRP). I made my first PBR shader and it works correctly when applied to a material, but it doesn't display anything on the Main Preview in the Shader Graph editor. I tried selecting any of the different options (display a sphere, etc) but nothing seems to work.
Preview doesn't work either, for instance, on a Multiply Node with a color and a fresnel effect as input. Instead of a sphere with the fresnel effect and the color there's just a black square, same as Main Preview.
I made an unlit shader (with Shader Graph) and it works fine, preview displayed and all.
Any idea how to make the preview show in PBR shaders?