I made an item in Forge 58.0.6 that has a 20% chance to apply poison 1 for 10 seconds. That works perfectly.

 

But the texture doesn't show up. I've tried replacing the texture with a basic minecraft:item/iron_sword but it still loads the purple and black box texture. Running the mod in IntelliJ and in the Minecraft launcher yields the same result. There was no error in the console about missing textures or models.

 

IDE: IntelliJ

git: https://github.com/LeeveyG/Leevey-s-Armory.git

Edited August 16Aug 16 by Leevey

Maybe you need to create file in assets/<modid>/items/<itemname>.json with content like this:
 

{
  "model": {
    "type": "minecraft:model",
    "model": "modname:item/itemname"
  }
}