If you recently changed time zones this may have caused your statistics to not register correctly.
Please check your session log and if need be manually add missed dated sessions (Profile > Settings > Journal, Log and Stats > Session Log).
If this is not the case please Submit a Question form with your login email address and one of our Customer Support members can investigate this for you.
Please Note: Known Issue
We are aware for a small percentage of Android users, their stats and charts are not displaying accurately.