The focus@will Productivity Tracker is activated for sessions longer than 20 minutes. If you are doing shorter sessions than that you will not be prompted for Productivity input.
You can also check to make sure your Productivity Tracker is "ON". You can do this by tapping the menu (three horizontal lines in the upper left-hand corner), then tap "Productivity Tracker". The "On/Off" toggle is at the top of the screen.
Comments