Cloth simulation not animated in 3D Viewport I'm following this tutorial, and came to the step where I start the physics simulation for a piece of cloth dropping on an object (11:25 on video);

When I press the "play" animation button, the cloth that should fall on the object does not animate, and nothing happens except the animation marker which plays. 

I cannot get the cloth to animate as it does on the video tutorial, what can I be missing?
It seemed to work after waiting a few seconds when the play animation button was clicked. It took some time for it to actually start animating.