When I punch a horse with armour on, rendering them invisible, my screen turns black.
I can still interact with the game until I click outside of the screen. It then apparently opens the escape menu as seen on the screenshot.
First screenshot was taken a few second after the screen went black, the screen is red on the image but for me it turns black.
Second screenshot was taken after I clicked away and into the game window a couple of times, interaction no longer seemed possible.
Third screenshot was when on the LAN server's computer it said I had left the game.
I find this one especially strange because I was no longer on the server, yet I was still able to take a screenshot.