In order to prevent over-calculation of steps there has been a data save tolerance of 30 steps. So, the tracker will not store step counts that are less than 30 steps.
The tracker will also not start displaying real-time step counts until you reach 10 steps.
The tracker has this tolerance so that it does not pick up movements done during most daily tasks.
If you would like the tracker to count every step then you can use Sports mode to have it actively count all your steps.