Is there a contradiction between the Hadith that the braying of a donkey indicates its sighting of a devil, and the Hadith that devils are chained during Ramadan?

The two hadiths are authentic, and there is no contradiction between them. The chaining of devils does not prevent their sight, and it is possible for devils to be chained yet remain visible. Some scholars have mentioned that only the rebellious devils are chained, or that what is meant are those who eavesdrop.