Testers can't sign up for a teen age (13+) content beta claiming they need to be 18

We are trying to build up our beta testing player base and I'm having difficulty suddenly with allowing users to test the game if they're under 18. The content rating for the game is set to 13 plus and I went into each live build and clicked confirm on the age settings but they still are getting the same message. Any help would be appreciated thank you