This is something I also realized recently. Sometimes this happens, sometimes not.
Rebooting 2 or 3 times *could* make the picture visible.
This issue seems to be a bit different to the "no signal" issue with 4.4 kernel. With 4.4 kernel on my hardware it shows the message "no signal", with 4.8 it displays the correct resolution instead. But sometimes it just shows a black screen. When I start a movie it shows up, just the menu is missing. When the movie is finished again there is only a black screen.