Infoblox Captive Portal will not pass the "Accept" screen on Iphone or ipad 6.1.2

I am learning there is an issue with 6.1.2 with Captive Portal services where the latest IOS release will not progress beyond the terms and conditions. The next step in the authentricatoin process is certificate check so it would appear Apple has altered the process?

We have a lot of users complaining now but only 6.1.2 is affected. I have checked previous version on other devices and there is no issue.

Thanks

Ken