Hi Aaron and Darren,
I just copied Aaron’s app and this is was the action on the button.
And I published it on my end too but doesn’t showed and only the first item of that rel showed.
I’m guessing if the issue is that? 
I added a new button and the Show New Screen Action points to This Item and on the other screen I added that rel on the inline list and I see that in the builder and the preview too!
Check here : franse woordjes
Thank you