When I DC in game, the auto-reconnect feature never works. I ALWAYS have to manually close the game then re-launch it (also why do I have to wait 5 seconds to close the game if the game knows I've disconnected????).
When I am in the launcher and I put my computer to sleep, then wake it back up, the auto-reconnect never works there either. I always get the "We weren't able to reconnect you to League of Legends" message then have to manually re-launch the launcher.