Android : libgdx updating scene when app goes invisible

I am using libgdx's render() function to update scene with time delta, and then draw the scene. However, when the app goes invisible, the render() function is no longer being called, which causes the scene to stop updating, E.g., an animation will stuck at the last frame, until app goes back to foreground.

The problem is that I am building an online real-time game which cannot be 'paused' on client. When the app switches to background, the game must keep updating the scene even without drawing the scene, so that when the user switches back to the app, he can see the most up-to-date scene, instead of a pause-and-resume scene that lags back.

My question is how to achieve this in libgdx, so that the scene keeps updating even when app goes background? Does anyone experience the same problem as mine?