I know this was partially answered already, but for anyone still trying to get this to work with the Sprite Custom Lit shader, this seemed to work for me:

Create a Texture2D variable and make sure its Reference is set to "_LightTexture_0_0", and disable the Exposed checkbox.

This should grab a hard reference to Unity's built-in 2D lighting render target which you can use in place of the 2D Light Texture node.

Not sure why the 2D Light Texture node is bugged here either, but it's probably a simple fix for the Unity devs. I'll see about opening a ticket and getting this patched if no one has done so already.

In the meantime, I hope this works for others!

I know this was partially answered already, but for anyone still trying to get this to work with the Sprite Custom Lit shader, this seemed to work for me:

Create a Texture2D variable and make sure its Reference is set to "_ShapeLightTexture0", and disable the Exposed checkbox.

This should grab a hard reference to Unity's built-in 2D lighting render target which you can use in place of the 2D Light Texture node.

Not sure why the 2D Light Texture node is bugged here either, but it's probably a simple fix for the Unity devs. I'll see about opening a ticket and getting this patched if no one has done so already.

In the meantime, I hope this works for others!