There are two main reasons why it stays sticky.
The first is that it is hot. If you are in a climate with high temperatures or you are a person who tends to have very hot hands, this heat is transmitted to your sugar paste.
On the other hand, we find humidity. Perhaps, you live in a place with a large amount of humidity and this affects our fondant.
But do not despair, I bring you how to stop fondant from sticking to your hands.