Permit drawing over other apps grayed out When I open an app that needs permission to draw over other apps, this screen pops up. But for some reason it is grayed out and I can't allow the app. How can I allow the app to draw over other applications? Why is it grayed out?

My device is Galaxy s7 edge running android 6.0.1
Just had this with an app that wouldn't launch - beeshyams is right, the cause is one or more "enabled" apps that have permission are blocking it - probably not that the problem app needs permission.  Go to the list of apps with permission and disable them.