1.17 Custom Model Data Not Working

I'm not sure where my problem is stemming from, as I have several dozen custom models working in the current test resource pack I'm trying things out within. So, I've been trying to add a few new models, the models work individually when I place their file path in the "parent" directory, but I can't seem to get them to function with the Custom Model Data like I have in my previous models.

Saved as: "oak_sapling.json" in the "model/item" folder.

{
"__comment":"Made by Lew",

"parent": "item/flora/tree_apple_sapling",

"textures": {
    "block":    "item/flora/tree_apple_sapling",
    "particle": "item/oak_sapling"
    },

    "overrides": [
        {
            "predicate": { "custom_model_data": 1 }, "model": "item/flora/tree_apple_sapling"
        },
        {
            "predicate": { "custom_model_data": 2 }, "model": "item/flora/tree_apple_mature"
        },
        {
            "predicate": { "custom_model_data": 3 }, "model": "item/flora/tree_apple_flowering"
        },
        {
            "predicate": { "custom_model_data": 4 }, "model": "item/flora/tree_apple_smallfruit"
        },
        {
            "predicate": { "custom_model_data": 5 }, "model": "item/flora/tree_apple_fruited"
        }
    ]
}

Eliminating spaces, changing the item used for the model's base, changing the custom_model_data integer, moving the files to the "model/block" directory, and pasting in the format of other working files hasn't fixed the issue. I've been looking between the working files and this one for several hours and haven't been able to spot where its point(s) of failure is.

Help would be greatly appreciated.