Game Keeps Going When Paused

Okay so I was taking a break from playing on my survival world for a while, which meant I paused the game and went to a different window. But when I got back on, apparently the game was still going on when it was paused, the daylight cycle and all. It said I had died because I got slain by a Phantom, and because time was passing in the game, I lost all of the stuff I had on me, which was a lot. I don't know why the game would still go on like that when paused, and I wish something was done to fix this because it made me mad.