I'd provide you a few troubleshooting steps to check if this is a mobile application issue.
Temporarily, you can log in using a browser and check if your QBO works well. If it does, go back to your mobile app and clear the app data.
Click the Menu icon, then choose Help & Feedback.
Select Refresh Data.
Once done, you can close and reopen the mobile app and check if it's working fine. Also, I'd suggest restarting your phone. If the same thing happens, let's uninstall and reinstall the app to start a clean slate.