The embedded “App Bav” disappears in the mobile app under (in my experience, not too uncommon) circumstances, leading users unable to navigate within apps (well, mine at least) without leaving the app. It’s easiest to explain with an example — you can recreate this yourself. Grab the react-router-template and fire it up on a dev store with the shopify CLI and shopify app dev. Load the app in the Shopify mobile app and you’ll have a menu with the App Nav items:
Tap into the main shopify side menu (hamburger icon) (aside: notice that, if you’ve pinned the app, nav elements don’t show up under the app like I think they should) and then tap back into the app, either by tapping it in the sidebar or by tapping the side menu button again to close it. Now you’ll see:
The App Nav menu is gone! And the app name rather than the page name now shows in the page heading.
Hope that’s clear enough we can get a fix soon. Cheers.