A few weeks ago, Apple's Group FaceTime was discovered to have a major security flaw which potentially allowed users to listen in on others without their permission. The flaw was quickly publicized forcing Apple to shut down FaceTime servers temporarily while a patch was being created. A week later, Apple released iOS 12.1.4 which addressed the security issue and re-enabled Group FaceTime for those users.
Unfortunately, Group FaceTime even under iOS 12.1.4 hasn't quite been restored to its former functionality. A MacRumors forum thread started the day after 12.1.4's release revealed users who found themselves unable to add more users to a FaceTime call. As it turns out, it appears that users are no longer able to add a person to a one-on-one FaceTime call. The "Add Person" button remains greyed out and inactive in this situation. The only way to add another person to a Group FaceTime call at this time is to start the call with at least two other people. This slight distinction appears to be the source of confusion for many users.
MacRumors forum user Bob-K persisted in his support calls with Apple, and was finally told that the "Add Person" button not working in that situation was a known issue and that they didn't know when it would be fixed.
Apple Support on Twitter also appears to be aware of this restriction:
That's good. Also, note that Group FaceTime calls need to be started with at least two additional users in the FaceTime app. Meet us in DM if you're still having an issue with more users: https://t.co/GDrqU22YpT — Apple Support (@AppleSupport) February 15, 2019
We were able to reproduce this issue, but it appears this workaround isn't entirely reliable as one user reported being unable to consistently add people even during a group call. A search of Twitter shows a number of users who believe that Group FaceTime remains disabled, though some users may simply be unaware of the iOS 12.1.4 update, or may be confused by the greyed "Add Person" button issue.
Apple is actively working on iOS 12.2 Beta which has not yet seen the addition of the patch for Group FaceTime, but we'd expect them to address the ongoing bugs in a later 12.2 beta release.
