I have experienced the same thing since May 18th. I called Apple and they had not heard of such a thing....really? My text messages disappeared after the update. At this point I didn't have the icloud set up. So I already had an itunes backup. I then erased my phone, restored from my last backup and all my texts were there so it seemed. Actually it was every text thread but ONLY the last text sent. no previous conversations. Then I had issues with my voicemails disappearing. After erasing and restoring my phone several times, I finally go it back to normal. I setup my icloud and performed a backup. One day I turned my phone off and turned it back on(a normal thing to do..right!), it deleted my old original voicemails from my backup and pulled up the most current ones. My text messages were all deleted prior to my backup restore. All the ones after May 18th appeared. It's as if I have 2 different phones on one phone....if that makes sense. Could it be that when I turned my phone off and on, it pulled from the icloud instead of what I restored from my itunes backup? I have an iphone 6.