Earlier there was a glitch found in iOS 12 that allowed an attacker to break into a locked iPhone and access his contacts and photos. Here is a new bug, an embarrassing bug. It sends your messages and texts to unintended recipients. Think about it, you sending some rants to your little sister and they end up sending to your mom instead. Well, that’s shameful.
Apple had done some work under the hood to improvise the iMessage experience on iOS 12. The company did it with the intention of creating a single unified thread for contacts who using multiple numbers and email addresses. It all sounds good in theory, but the way Apple executed it has created a tumult across iOS users. Apple’s Communities Forum has received a number of complaints about the messages app. When sending a message to a combined thread then only that recipient receives the message that has left the sender message last time. And when you send a message to someone then that message gets into the combined thread. In both the ways, the message can go to someone for whom the message was not intended.
Some people suggest that somewhat the problem has to do with linked Apple IDs. One iOS 12 users posted a workaround and it works. Head over to Settings > Messages > Send and Receive. Tap on your Apple ID and sign out of Apple ID for messages. This workaround will force the devices using same Apple ID to use their mobile numbers rather than share Apple ID. Finally, you should delete all the threads that were merged.
If you are also experiencing the same issue, then hopefully signing out of Apple ID for messages will end your problem. Everyone else in the Apple Communities forum has considered this useful and still wants Apple to come up with a fix of its own.