I have the same issue. I often meet this issue when I unlock the screen before the black screen returns to the original screen. In short, when I unlock it very quickly, this issue happened.
Screen is successfully unlocked, but the only thing I get is a single mouse pointer and black screen. I can move my mouse, but nothing is on the screen but black.
Ubuntu 16.04, GNOME shell 3.18.5
I have the same issue. I often meet this issue when I unlock the screen before the black screen returns to the original screen. In short, when I unlock it very quickly, this issue happened.
Screen is successfully unlocked, but the only thing I get is a single mouse pointer and black screen. I can move my mouse, but nothing is on the screen but black.