I tried animating with my Minecraft rig, and for the first few hours it was working and it even shows in the rendered view, but when I did put it on render view, the rig can't be seen. I don't know why it happens like that.
I looked at it, you said it isn't render restricted, It IS. Your rig has a visibility driver system that turns its visibility on and off. I don't know where the controls are, I only know it because I see a lot of drivers going in and out of its restriction settings. I would just delete them if I were you. But if you wish to make use of this function, I think it's best to contact the author for manual.