Having a go at my first PowerApp. Very simple - I have a sharepoint list which it's integrated to - plan is to open the App using the URL to pre select the record. Landing page is just the form in view mode, with an edit button to one side. Click the edit button, switches the form to edit mode, save/discard buttons pop up, save submits form then takes you to a confirmation page, discard switches back to view mode.
Haven't passed in the URL variable yet, just have a specific record identified in the on start.
This all works perfectly in the editor preview, but starting the app from the URL or the list of apps I get
Tried a few things I've seen on threads for similar issues but nothing seems to work.