The custom mob model does not damage the opponent

Hi everyone, I need some help with custom mob models.

Finally I managed to make a working Custom Mob Model for Minecraft 1.12.2 (using Tabula), but for some reason, while in attack phase, it runs against the opponent without doing any damage. I think there's something wrong with the model, since the mob worked properly before the model (default model) was replaced with the new one (custom model).