Apple released a statement on Monday saying they identified the bug and are working on a resolution. In the meantime, Group FaceTime is unavailable, as per the Apple website.
The bug functions on iPhones and iPads running iOS 12.1, and Apple PCs running macOS Mojave, which have the recently added the Group FaceTime feature.
It’s activated once someone FaceTimes you, swipes up to add another person to the call, but add their own number instead. The person who made the call is able to listen live via audio on the other person’s phone although they haven’t accepted the call. What’s even crazier is that the screen doesn’t even give any indication that the call is being connected. If the person receiving the call presses the volume button to dismiss the call, the caller can see live video of the other person.
To avoid being a victim to the failed bug, turn FaceTime off on all your Apple devices until it’s fixed.