Did you send a request to Customer Support? If not then please answer some of the following questions.
-When did you notice this issue begin? Please provide dates and times.
-Are you able to receive invites or unable to send/receive? If you can send invites please let us know.
-What game mode are you trying to invite other players to?
This information will help us understand what is going on. Once again if you have sent a request to Customer Support make sure to provide them with this information.
-WGTyphoon