I've made a half-slab with multiple textures but it only renders 1 flat side, but how can I make it so it renders it the same way as normal slabs?

Block model:

{
    "textures": {
        "0": "km:blocks/fast_belt_front",
        "1": "km:blocks/fast_belt_side",
        "2": "km:blocks/fast_belt_top"
    },
    "elements": [
        {
            "name": "Cube",
            "from": [ 0.0, 0.0, 0.0 ], 
            "to": [ 16.0, 8.0, 16.0 ], 
            "faces": {
                "north": { "texture": "#0", "uv": [ 0.0, 0.0, 16.0, 8.0 ] },
                "east": { "texture": "#1", "uv": [ 0.0, 8.0, 16.0, 16.0 ] },
                "south": { "texture": "#0", "uv": [ 0.0, 0.0, 16.0, 8.0 ] },
                "west": { "texture": "#1", "uv": [ 0.0, 0.0, 16.0, 8.0 ] },
                "up": { "texture": "#2", "uv": [ 0.0, 0.0, 16.0, 16.0 ], "rotation": 270 },
                "down": { "texture": "#2", "uv": [ 0.0, 0.0, 16.0, 16.0 ], "rotation": 270 }
            }
        }
    ]
}

The item model is the same

If I'm reading this correctly, it probably has to do with the rotation of the block in the inventory try adding this to the top of your model json

"parent": "block/block",

 

Thanks, it works!