If it is said, ‘How is it that we see many evils and acts of disobedience (occurring) in Ramadan? How are these things happening if the shayaateen are chained up?’
Then the answer is that (evils and disobedience) are only lessened for those who observe the fast while preserving its conditions and etiquettes. Or (one can say) that only some shayaateen are chained and those who are chained are the major ones (not minor)…and this has been mentioned in some chain of narrations. Or the meaning could be that the occurrence of disobedience is less in (Ramadan) as opposed to the other months.
Even if all of the shayaateen were chained, then this doesn’t mean that evil and disobedience would never occur. There are other reasons which influences disobedience to occur. For example: people having evil souls, bad habits, and the human shayaateen.
Source: Fathul Baari