cracks on the surface of a cheese are the result of errors in pressing.
Most likely, I find that the error amateur cheesemakers make the most when pressing is that they do not flip it enough.
If you flip it just a few times, you will have folds and maybe even cracks. If you flip it many times, each time you do so the cheese becomes smoother. Also you may have cracks if your curd is too cold when you press it.
We flip our cheese 7 times during the 20 hours it is in the press. The standards for the type of cheese we make call for it to be flipped at least 6 times.
By flipping the cheese so much, you ensure a very nice, even pressing as well as a good smooth rind. You will find that if you have problems with making lopsided cheeses, flipping often also helps take care of this.
So how do you solve issues with cracks and folds? flip often, and press long and hard. And press warm.