Hi. I have, exactly, the same issue. I´m typing from Brazil. I went to a Apple Service in my city and the guy perform the same test: he used his finger to color the screen and a strip appears on the left side that was irresponsive. What country are you? Please.UPDATE:
Hey guys so I went to the Apple store yesterday about this issue. The Genius nice dude, did a bunch of tests. Finally he did a display test where he used his finger to color in the screen blue where he found a strip going from the top and bottom of the left side would not respond to his touch. Concluded as a hardware issue. Hour later I was out with a brand new shiny display for my XS Max. Great service probably helped I had AppleCare+