A fault has developed with the app.  The solution is, when you choose the "Add tracking number" option and the screen appears without the 'Scan' option, choose the 'Add another tracking number' option and a second dialogue box opens with the scan option.  Then choose the 'Remove' option and the dialogue box without the 'Scan' option disappears.  Then use the 'Scan' option as usual.  Message me if you need additional help or information.😀