I'm trying to make a '3D ore' resource pack, but I'm getting a lot of weird rendering and culling errors.

If I make a new block model, all sides of all boxes that face another block are rendered solid black, regardless of any declarations in the json files. Additionally, the face of any other block touching this one is culled when it shouldn't be. I've tried basically every combination of texture and uv parameters, all options with 'cullface', and declaring the 'to' and 'from' of boxes to be reversed (inside out), but absolutely nothing works.

In the example pictures I changed the sea lantern blockstate to point to the vanilla anvil_undamaged model and I get the same thing, so it's not a case of me writing a malformed json file.

{

    "variants": {

        "normal": { "model": "anvil_undamaged" }

    }

}