Note that for 2D item models, you need to copy the item/generated vanilla json and put it inside your block models folder to use as a parent:
https://github.com/Draco18s/ReasonableRealism/tree/master/src/main/resources/assets/harderores/models/block/item
https://github.com/Draco18s/ReasonableRealism/blob/master/src/main/resources/assets/harderores/blockstates/largedust.json#L4