Why does the myPhonak App show different Wearing time values?

The sum of time spent in different sound environments is different from the Current value and the Wearing time graphs

The Current Wearing time (in dashboard and daily view) is updated every minute. The sound environments (Calm environments, Noisy environments, Music and Streaming) are updated hourly and the daily graph is updated when taking hearing aids out of the charger and every time the synchronization with the hearing aids is done (manually or automatically).