Just wanted to check if you have Accidental Touch protection enabled?
The s8 in general is defective. This Device has fried my $90 SD card (Linux will not even mount the partitions) and the screen has had ghost touches since I walked out of the store. It has been impossible to type from day one. Forget with a screen protector because then it won't even recognize touches. Typing this even I have to delete half of what the keyboard is attempting to input. I had been refused a device exchange while still in my 90 days of purchase and now it's safe to say I will never be purchasing such a low tier phone again. I have to remind myself that I need a phone every time I raise my hand to smash this piece of junk