Your charts are on an online or server-based system, which means internet signal is required in order to load activity charts in the app. Please make sure you're on a reliable wifi or data network when you try to load charts.
Check all anti-virus and ad blocker apps installed on your phone/tablet to ensure these apps are not blocking the Striiv app from internet access. Also, try logging out and logging back into your account - the log out function is under user settings in the app menu. Still nothing? Shoot us an email at firstname.lastname@example.org and we'll help you out!