Reinstalling Rocket League can sometimes fix odd problems. You will first need to 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].