dungeon chest not spawning

sirbad2012

My group and i alway do a dungeon during the dungeon delve event so we can use our keys at the end but for some reason ever since the very first dungeon there has not been any chests spawning that require the keys to open its very frustrating. I make sure its during a delve event. But still only a standard chest spawns no additional chests spawn. Please help cause we feel we r missing out on good loot. Thank you