In the App Store version, Diagnostic Reports has no Export Log. Logs can only be attached, in their most recent part, through Upload to the Author. TestFlight builds can export the full log. The Mac diagnostics window has Export Log.
Overview
In the App Store version, Diagnostic Reports has no Export Log; logs can only be attached, in their most recent part, through Upload to the Author. TestFlight builds have Export Log, and so does the Mac diagnostics window.