If you have recently logged in, your account may still be syncing and will need a few minutes. If the problem persists, log out of your account through the app "Settings" page and log in again. This should resolve any sync issues that may have occurred.
If you recently updated the app or the problem persists through a log out, delete the app and reinstall it on your device. If you're still not seeing any of your items, email firstname.lastname@example.org