If you have thousands of contacts, then one of the features of our app might be preventing you from seeing messages and call history. Thankfully, it's easy to turn off that feature and everything else should work just fine. To disable this feature, you need to enter a special sequence of digits in the Grasshopper dialer page, and then try to refresh messages again.
The sequence is: *637136#, then press Call
After entering the characters above and pressing Call, it should disable a feature that might be causing this issue for you. After that, you can close the app, and then come back to it an refresh messages. Please don't uninstall the app or sign up, since that will undo what you just did.