You’re offline. Practice still works and is saved on this device; videos need a connection.
A question you answered comes back a few days later, so you can check it stuck. This page gathers what is due from every lesson. It reads the progress saved in this browser, so it only knows about practice you did on this device.
Checking your progress…
Use the same browser you practice in. To bring progress from another device, use “Move or reset your progress” on each practice page.