Fortnite crashes and both monitors flash black?

I have 2 monitors, on the one I play Fortnite and on the watch I yt etc. Whenever I press the win button (tab + alt) to get on my other monitor, it is then but first if I then change back to Fortnite both monitors flash black and Fortnite smears off, what should I do?

No Fortnite play anymore! Fun (I'm not a Fortnite player MORE)

So maybe you have to find a different key combination because Alt + Tab is to raustabben and that can buggen when playing…

Fortnite does not crash, but both screens turn black for about 1 sec