The thing is that you’re using your phone as a light source, and on a sunny day its brightness is insufficient to give a well visible reflection.
Initially, the idea of the app was to facilitate navigation in low visibility — when you can't see beyond 50-100 meters. This is where it will be most helpful.
If you’d like to use the app in daytime, we suggest that you try HUDWAY Cast. It’s a HUD device that wirelessly connects to a smartphone and brings directions in your line of sight. You can learn more about it and order it at hudwaycast.com