Reinstalling Rocket League can fix some problems. You will first need to uninstall, then redownload and install Rocket League again.
To uninstall Rocket League
- Press the Xbox button on the controller
- Select the Profile & system menu
- Select Settings
- Select System
- Select Storage
- Select Internal
- Select Uninstall
- Select Rocket League
- Press Remove selected
To re-download Rocket League
- Press the Guide button on your controller.
- Select Xbox Home
- Select Settings
- Select Account
- Select Download History
- Select Rocket League
- Select Download Again