This had happened with my iPad pro 10.5 after having it for 1.5 years . The sound had been cutting out intermittently when using the wired jack for about 2 weeks prior ,I initially thought it was due to the headphones themselves but after aboit a week the iPad would randomly freeze and be stuck on grey Apple screen if it was allowed to time out into sleep mode , it would only turn on again up if hard reset . This happened a few times until I contacted apple support which advised me to do a factory reset.. that was what ultimately killed the machine . Everytime it tried to install the OS from iTunes from any computer using different cords it would flash red for a couple seconds then fail and error code. . Genius bar couldn't help me as it is out of warranty . I used the iFixit repair guide to open the screen and immediately saw the problem. A piece of the earphone jack.had dislodged and a tiny screw was free inside . Im not sure how that happened in the first place but as soon as I put the screw back into place and closed everything back up the iPad booted as factory reset and I was able to restore data from last backup. the iPad works perfectly now . No sound issues ..not a software problem .it was a hardware problem at least for my case.