So I'm working on a mod that adds new weapons to the game, but when I added the texture for one of my items it renders weird in the inventory. As you can see, the item in question looks identical to the vanilla iron sword, rendering perfectly both as a dropped item and as the model help in hand, it's only in the inventory itself that it looks all crooked.
The item texture was originally 18x18 as opposed to the default multiple of 16 (64x64 I believe). The problem persisted even when