After completing games, I am not receiving any notification on gaining any key fragments. I'm not sure whether they pop up on screen like a mystery gift, or appear in the chat, but I've been checking both of these things in the end-game lobby and I have had no notifications of keys but have been gaining them. The only current way for me to check is to actually go into the hextech tab and look myself. I have been receiving chest notifications.
Game Mode: SR Ranked
Reproduction rate: 3/3