I usually do not have many issues with this game but I just leveled up and I didn't receive a dark hours apparel cache..Is there a cap on how many you can get in a set period of time or is this just a glitch of some sort?
Other posts in here are absolutely correct. There is a chance to get keys from caches, not a guarantee. Additionally, there is a limit to item obtainable through the Apparel Event.
Best of luck!