11-18-2021 8:55 PM MST- I have the same iphone12 mini touch issue. Here are the specifics: new iphone12 mini (5 days old). Purchased via my local in-town ATT store. Running 14.2, case is new Otterbox Defender purchased and installed by ATT staff in their store at time of purchase. They also installed a flexible plastic screen protector at the time of purchase. Problem is odd- When phone is locked and a phone call comes in, the slide to answer swipe does not recognize any of my 10 fingers or their tips or any of my 10 fingertips moistened; however, the swipe to answer does recognize the rubber stylus on the end of a ballpoint pen, and does recognize at least one other person's fingertips and allows them to answer such incoming calls. NOTE- when the phone is unlocked, my own fingers can answer an incoming call normally. So the non-response to my fingers swiping to answer only occurs when my phone is locked. Once unlocked my own fingertips work just fine for answering incoming calls and for all other phone functions; the issue only occurs when my phone is locked and an incoming call is tried to be answered with my fingertips. I showed the defect to staff at the ATT store at my point of purchase and they said it was "an Apple problem and to call Apple support". I did this this morning and spent 2.5 hours on the phone with senior advisors in their Accessibility section and they ported onto my phone (while it was hardwired into my laptop), we looked at multiple setting, unchecked all phone restrictions, and the swipe worked just fine with my fingers to answer calls while hardwired to my laptop. Thinking the issue solved, I unplugged my phone from my laptop, and went about my business. Later in the same day I found that when the phone had autolocked based on time, the issue recurred and my fingers would no longer allow me to answer an incoming call. I re-called Apple support tonight (11-18-2020) to report the issue, spoke to a senior advisor again for another 1.5 hours, and told them I wanted to register my iPhone12 mini's serial number as one having this issue, and that I had seen similar touch screen issues involving locked screens reported on both MacForum and here on macrumors. The senior advisor tried to blow me off to an Apple website to report this issue, and I refused her offer, and insisted she verbally confirm the serial number of my non-functional iPhone 12 mini. She acknowledged the issue I was having with this $800+ purchase, confirmed my phones serial number, searched her resources, and admitted "Apple is aware of this issue with iPhone12 mini touch screens, and is working on a software update. That a software update would be coming soon." I asked how soon, and asked if it would be hours, days, weeks, or months. She said she didn't know. She said I should check for updates every 2-3 days, and that when it was available it would be pushed out via the Automatic Updates function if that was enabled on an individual's iPhone12 mini. She further advised that the 1 year warranty from Apple on the iPhone12 mini allowed only for replacement of a non-functional iPhone12 mini with another iPhone 12 mini. I asked if that replacement would be functional. she said it would be an identical replacement and could not guarantee functionality. I asked if it was also non-functional could it then be replaced with a third replacement for free, and she said yes, but again with no guarantee of functionality. She said if an individual wished to downgrade from a non-functional iPhone12 mini to a functional iPhone11, or upgrade to a functional iPhone 12 or 12 Pro, that would have to be done within the return time window of the carrier (14 days in my case) and through the carrier's store (ATT in my case).
UPDATE 11-19-2020 11:40 am MST - Problem swiping to answer an incoming call seems only to occur when the phone Autolocks (based on my time setting). Does not occur when I manually lock my phone. Temporary solution is to set Autolock to Never, and use manual lock instead.
