I found a bug related to the smithing table recipe type and item models. Basically after an item has the item model component you can't revert it back to the default model.

To reproduce this put the diamond sword with the 2 gold blocks, doing this gives it the golden sword model. Then put it with the amethyst, it gives it the iron sword model, which successfully replaces the gold one. Finally, put the sword with the diamond blocks, you'll see that instead of reverting back to the original diamond sword model (which is specified in the code,) it still has the iron sword model.