"No Item to Display" on multi-screen SharePoint Form

Since I see the SharePoint Integration formula in your efforts, I'm going to assume this is an app created using "Customize Forms". In that case, you want to check on subsequent pages what the default mode of each form control is. Important thing here is that if the default mode is NEW then it completely ignores the "Item" property. (The display of "No item to display" seems to give me the impression the default mode is new.) - Let me know and I'll help you to get what you expect.

If this is a full 3-screen app - created using Create an App rather than customize form:

Try running the app in preview (assuming this is a 3-screen app not the customize form), and selecting something in the first gallery. If this is a three screen form you don't need to put any if statements to handle the lack of selection (unless they go to that form first before they hit the first screen). The new icon should include NewForm(FormName) so that the form moves into NEW mode when they arrive. In this case, the default mode should be edit, so that nothing special has to be done from the details form.