Hey there! If you are not receiving any invites, navigate to PS4 Settings > Account Management > Privacy Settings > [Login here] > Personal Info - Messaging > Messages. After that, set Messages to: [Anyone]. You may also want to delete your app cache by going to Settings > App Settings > Delete App Cache. You may also want to delete Content Database so it can refresh the companion app. Otherwise, you can do a full uninstall of the app.