According to this post: https://itch.io/t/380227/im-a-contributor-on-a-game-but-it-doesnt-show-on-my-pro...

There should be an option in the Theme Editor to show a hidden game that you contributed on, but I don't see it.  Has this feature been moved or removed?

Jacob

I figured out how to do it, you need to Edit your “Profile Theme” where all your games exist not the specific “Game Theme”