Shader Graph: Objects have no shadows opposite the Main Light

Broken Shadows?
I’m working with Shader Graph for the first time in URP and have run into an issue. I just finished adapting a toon shading tutorial into the Graph and everything works except the shadows: while objects cast shadows just fine, they seem to have lost all shading / light data on the side opposite to the main directional light, like self shadows are messed up. Normal bias is not strong enough to cover these faces, and they received lighting direction just fine until Shadow Attenuation was added to the lighting computation. Any advice?

With shadow attenuation removed:
With shadow attenuation disabledt

I actually managed to find a weird solution on my own. I tried using a darken blend node instead of multiply, which seems to allow support of both cast shadows and a gradient override for the object shading! This did result in less intense shadows, so I had to turn shadow strength back to max and use a blend value of 1.2.