numbers are no longer displayed (blank)
Please delete the connected Google account and then add an account.(How to delete your account)
Settings > Preferences > User Preferences > Edit button > Delete
(How to add an account)
Settings > User Settings > + button
If the above does not solve the problem, please delete the app and reinstall it from the store.
If you have already purchased a Pro license, you can also restore it.
Purchased a Pro license but the ad appears
If you have reinstalled the app after changing handsets or deleting it, you need to restore it.(How to restore)
Settings > Purchase Pro License > Restore