Today, I have found one of the most terrible bugs in Universe Sandbox 2, which has ever been found. When colliding gas giants with bigger rocky planets, the rocky planets disappears completely. This is abnormal and must be fixed as soon as possible.
As you can see in the animated GIF image below, the giant rocky planet disappears when the gas giant Jupiter crashes into it.
This is probably one of the most severe and worst bugs which has ever occurred in Universe Sandbox 2. Celestial objects should not disappear at all when they collide with one another.