An mind experiment, taking the entire Earth as an isolated system
Then this is the initial state:
N masses are distributed around the earth, at different height. (for example we can use a single grain of sand from one building of every city of the world)
Heights are not specified, can be choosen randomly, and those different initial dispositions microstates $\Omega1$ are equivalent to the macrostate (initial state).
the next step
The N masses are released and fall because of gravity
Finally all the N masses lie in its floor, they have become all closer each other, and the height now, relative to it's reference floor, are all equals zero. (If we take a sphere model then it will be zero height, same radial position for all)
So, at final state there are fewer possible microstates $\Omega2<\Omega1$, for the same macrostate, then if process was isolated. Why did entropy went down?