https://www.gamespot.com/articles/bungie-finally-addresses-destiny-2-chest-cooldowns/1100-6453667/

Since Destiny 2's launch, players have been left in the dark regarding the way chest cooldowns work. Much like in the first game, players seemingly hit a temporary cap where they no longer obtain anything by rapidly opening chests in a short span of time, but this is not communicated clearly in-game. Worse, it seemingly affects the chests located in Lost Sectors and those you earn by purchasing Cayde's Stash maps, which can be downright frustrating--those maps cost money, and players are sometimes getting nothing for tracking down the corresponding chest. After a period of silence, Bungie has finally discussed the matter and confirmed an apparent bug with the way chests currently operate.