Reinstalling Rocket League can fix occasional problems. You will need to first uninstall, then redownload Rocket League.
To uninstall Rocket League:
- Select Settings
- Select System Storage Management
- Select Applications
- Highlight Rocket League
- Press the Options Button on the controller
- Select Delete
To re-download Rocket League:
- Select your local user account and go to Library
- Select the game or add-on you want to re-download (add-ons are in a folder with the main title)
- Select Download on the content screen
You can check the progress of your downloads in [Notifications] > [Downloads].