The bluebot device was designed to accurately and repeatably measure flow in any direction. There is no “backwards”, like with many other meters. Assure you have found a proper section of pipe that is clean and clamp it on tightly.
If you would like to speak to a member of the bluebot team, simply navigate to Settings > Support from within the app and choose your preferred method of communication. Otherwise, you can email firstname.lastname@example.org