Hey Bardygrub,
I am sorry to hear that you are unable to receive or send invites. Please try to unlink / relink your gamertag. You might want to create a new Call of Duty account using a new e-mail address. Also, we are aware of various clan functionality issues that some users are experiencing, and we appreciate your patience while Beachhead keeps working on improving the app functionality. You can visit this link for any updates: Beachhead Studio (beachheadstudio) on Twitter
Sincerely,
^CA
ATVI Support