I've got an appointment at the Genius Bar on Wednesday, but I figure I'll throw this out to the in-house experts in the meantime to see what you think. Here is my sad story: For the last few years, I had an iphone 6 with 16GB storage, always updating to the latest software when it came in. For the last year or so, every once in a blue moon -- and I'm talking like 1 time out 100 -- my autolock, set on one minute where I like it, would not engage after I sent a text. The screen just stayed on and on until I actively turned it off. I contacted Apple support a few months ago about this problem, and their best guess was that since my phone was near maxed out on storage, strange things were happening. So I gave up on the problem and tried to move on with my life. Two weeks ago, I bought an iphone 8 with 256GB storage. I took it home and restored from backup, and looked forward to a perfectly working new phone. Only I didn't have one. Once again, maybe 1% of the time, my screen stayed on after I sent a text. I called Apple support, and they speculated my restore had brought over old bugs and sugggested I set up as new, with no restore from backup. So I set up as new. Same problem. I call back Apple support and told them. They theorized since I set up my iphone as new from the phone itself instead of plugging into the computer and doing it through iTunes, I had brought back the same problems. They then walked me through the lengthy process of setting up as new once more, this time through itunes. We synced up contacts and such, and reloaded apps from the cloud or whatever, and they said I should be good to go. I wasn't. The problem returned. I called back Apple Support, who had no real answers, and I then decided "the hell with this device. Maybe it's defective. I'm taking it back to Best Buy and getting an entirely new one". A true fresh start. So that is what I did. I took home my second new iphone 8, set up as new via itunes and all that tedious stuff, again avoided any "restore from backup", and figured I was problem free. I wasn't. A few days later, the problem resurfaced. It has now followed me to a third device. The only difference now is that for the first time I noticed the screen remaining on after an incoming text. All previous times, I only noticed the problem on outgoing texts. (I've never noticed this problem on anything other than text messages.) This time I didn't even bother to call Apple Support, but set up an appointment at the Genius bar for Wednesday June 13. So there you have it. A maddening problem, one made more maddening by the fact that it happens so rarely and unpredictably. I can exchange two hundred texts over a few days and never have a problem. But sooner or later, the screen stays on until I turn it off. Then it's back to normal, until it no longer is... Anyone have any thoughts on this conundrum?