This occasionally happens in mysterious ways for certain WiFi networks or mobile carriers in certain regions due to API connectivity issues.
Steps to fix:
1. If you are using WiFi: Simply restart your WiFi router. This usually fixes the problem.
2. If that doesn´t help, try switching your data source from Wifi to cellular data or vice versa.
3. If switching the data source also doesn't help, then try completely restarting both the phone and app (close and restart the app).
If that all doesn't help please let us know ASAP!