May work for a while, but problem returns. This seems internal to the phone app itself and something Samsung should get up and fix. Got a $1000 phone that can't even perform well as a phone....makes my old flip phone look pretty darn good right now.
Called Samsung tech support and they tried this and that, even the above "fix" and still the problem exists. What a phone.
'No Screen Off' worked for me on S10+ until latest android update. Then nothing I could do could stop screen blacking out while on speakerphone. I'm trying 'No Screen Off Extra' now.
Samsung are showing a callous disregard for people's needs (it's primarily a phone FFS) by refusing to provide its own built-in solution to their phones' functionality.
Kin screen didn't work for me. Good luck.
I'll add my disgust here and continue about my day looking for a solution from someone even though the OEM samsung has no answers or fix for this extremely anoying S9 bug/feature. Thanks samsung!
The KinScreen app in the play store will keep the screen on during calls when using speakerphone. It's a free app.