Hi! I had the exact same situation. Upgraded from a 6active to 10S and I can't get my phone to go dark when I'm on a call but when I'm on a conference call using my earbuds, it goes dark.
They make tou spend so much more on a Phone that doesnt understand the difference.. what ever happened with your s10?
I've had mine new phone for 3 weeks and to replace with AT&T would be a refurbished phone and I didn't pay for a refurb.
I have problem with my s10+ exynos.
When calling and the phone is on my ear, the screen turns off.
However when moving my phone away from my ear the screen stays off during the call.
I have to push the power button to wake the screen up.
With my s7 edge the screen used to turn on when I moved my phone away from my ear when in a call.
Also when dialing *#0*# for the test menu's, clicking the sensors butten doesn't show any proximity sensor at all?
I also removed the screenprotector and the issue happends with both case on and off.
Is this a hardware or software defect, or am I missing somthing in the settings?
Alrighty, if the symptom still occurs in safe mode I would recommend a service repair. You may have a couple of options with how you can go about getting the repair if you wouldn't mind sending us a private message here with your IMEI number we can check on those options for you.