Although it rarely happens, the following troubleshooting steps are known to resolve the issue:
• Turn airplane mode on and off again.
• Make sure the device has a good internet connection (Wi-Fi recommended). You may also try to connect to other networks.
• Close all apps running in the background including the game. After that, turn off your device for a minute before turning it on and see if that fixes the problem.
If you are still having trouble after trying out the suggested steps above, be sure to reach us at firstname.lastname@example.org or contact us via in-game Help Center.