Screen stays black when pressing power button

[Fantasian]

Is this a know issue? Sometimes when I press the power button the glance screen disappears but the lockscreen dosent show up. instead the screen stays black. after a restart the problem seems to stays away some time but after a while it is there like every time i turne on my phone. after nearly 10sec. the lockscreen finally shows up most of the time...

 

[Fantasian]

This appears on two of my Lumia 950 and on one 650

 

[Fantasian]

This also happens when a notification should turn on the screen.