Help with 3d helmet model for 1.12.2 mod

I need help with a 3d helmet model. I made the model and texture, but when i ran the client to see it in game, it didn't exist, i could't even /give it to myself, i tried to switch to a normal model, and then it worked, it was in the creative inventory and everything, it just didn't have the 3d model i made. So I switched it back to the custom model, and to my surprise, it was still in the game, but only had the normal model and not the 3d one I made. I am using an older version of mcreator (2021.1) and a 1.12.2 generator plugin