Your study time captures only the time you've actually spent studying in Voxy. Check this article for more information about How do we determine your Study Time?
Your Performance Page monitors the time you spend practicing your course. Be aware that your Performance Page monitors only the time it takes you to answer questions in your activities and you can select the length of time you would like to check your study time. By default, your calendar will show a period of 3 months (90 days) taking into account the current date. However, you just need to change the date in the filter to see the hours and number of activities you completed.
The same applies to the number of completed activities.
If you want to learn more about how your study time is calculated, click here!