No mobs spawn

Mobs (both passive and attacking) will not spawn in any of my minecraft worlds. It is not an issue with the difficulty setting or gamerule command. The existing issue on the website describes a issue where they spawn and then immediately de-spawn, but for me they do not appear at all. I first noticed this issue in 1.11.2 but it might have existed before that. I have a windows 8 Toshiba laptop.