Why does my screen go black when my hand is too close to the retina scanner? Galaxy s9

[Android Central Question]

Anytime my finger gets within an inch of my retina scanner my screen goes black. When I move my finger or whatever is covering it away the screen does a soft fade back. Started past few days. Have a single long vertical crack in the screen from a month or so ago. No other problems from the crack.

 

[RG129]

Mine does that occasionally. I just restart my phone and it goes away.