Samsung's default text messaging app has been sending out random pictures to equally random people and not leaving behind any evidence that it has done so, according to various posters on Samsung's official support forums and around the internet, and now there are a few other glitches cropping up, as well as some more details and an official statement from Samsung on the matter. The bug seems to spring from a recent update on T-Mobile and other carriers that gave RCS messaging capabilities to Samsung's latest flagship devices. Scheduled text messages are also being sent out prematurely or ending up in the wrong threads, and some messages are being shown as sent when they actually never made their way to the other party. The issue is limited to the default Samsung text messaging app, and does not seem to occur in other apps, even those that support RCS, such as Android Messages. Samsung, for its part, is aware of the issue and is working on a fix, to be sent out as soon as possible to affected devices.
Some users have tried troubleshooting this issue, but have found no relief. Steps taken include things like rebooting the device, clearing out the device's cache and the app's cache, deleting all messages, and even uninstalling and reinstalling the app. The bug does not seem to happen whenever a different text messaging app is set up, meaning that the default Samsung Messages app can only wreak its havoc when it's actually set as the phone's designated SMS app. This is because RCS messaging, like SMS messaging, can only be handled by one app at a time.
The bug first came to light in late June, but Samsung did not immediately respond to users' pleas. If you have a later-model Samsung phone, like the Galaxy S8, newest Galaxy J7 or Galaxy Note 8 or later, you'll want to refrain from using Samsung's official Messages app for the time being in order to get around the bug. There are a number of great texting apps in the Play Store that can handle SMS and MMS messages, and if you'd like to take advantage of RCS capabilities, Android Messages is a great app to try out.