Hi,
I installed the latest version of The Impulse Theme on my Live store and this theme version is built using Shopify 2.0.
However when I click customize → Theme Settings, I do not see the “App Embed” tab.
I contacted the Impulse theme developer and they said that part is controlled by Shopify so should contact Shopify Support
I contacted Shopify and they said I should speak to the theme developer 
I performed some further testing and downloaded trial versions of other Shopify 2.0 themes to the same store and the issue is present there too.
Strangely if I try the same themes (and my impulse theme) on a development store the “App Embed” tab is visible.
Its clearly an issue with Shopify so I have contacted Shopify support again to try and fix the issue.
Has anyone else encountered this problem?
Thanks,
Sam