Armors textures not working with shaders mod

Armors textures look broken when using custom shaders mods (1.17+)

If you are on 1.21.2 and greater (both server and clients) you can use the new armors creation method that doesn't use any vanilla shader to create custom armors, so it is compatible with the shaders mods.

More info here.

Old Fix Information

This bug has a workaround fix in ItemsAdder 3.0.3

Note: this fix requires you to have Optifine or a CIT mod equivalent (like CIT Resewn) installed in your game.

If you see broken textures make sure you are using ItemsAdder 3.0.3 or a more recent version. Also make sure you regenerated your resourcepack using /iazip (and read the hosting tutorial if needed).

Optifine 1.19.3 and 1.19.4 are currently bugged and I cannot do anything about that. They don't support my fix. We have to wait the developer of Optifine to fix that issue.

This is not my fault.

What was the cause of this bug?

Optifine issue

Optifine has a limitation which doesn't allow custom armors to work correctly if you have any custom Optifine shaders installed.

You have to disable the Optifine shaders temporarily or temporarily live with the issue.

I already contacted Optifine developer about this: https://github.com/sp614x/optifine/issues/6391

Iris Shaders issue

Iris has a limitation which doesn't allow custom armors to work correctly if you have any custom Iris custom shader installed.

I already contacted Iris developers about this: https://github.com/IrisShaders/Iris/issues/1042