I also have this issue - started in the past couple months. If the screen is off for a long time it works normally sometimes. If I have always-on display and touch the screen before waking it with the power button or home press, it works every time...
I've been having this issue for the past month or 2. Turning on "always-on display" at least lets me work around it mostly, but it doesn't help when you're in a call and take the phone away from your ear and the screen turns on. If this issue has b...