Akali Ult Cooldown Bug

Yesterday, I was playing Akali when I was disconnected from the game. I'd been having lag for a while during the match, until the client froze for over a minute and I had to close it and reconnect. After I reconnected, I engaged in a fight and used Akali's ultimate (which had all 3 stacks available), and the ultimate got a 30-second cooldown before I could use it again.

I used the ult only one time, meaning I had 2 stacks left - therefore, her natural ~2 second cooldown should have been unaffected. Later on in the game, I was disconnected again and the bug happened once more in the same way: I ulted once, and the ult got a 30-second cooldown again.

The bug only happened once each time after a disconnect, and only the first time I used the ult. After the initial 30-second cooldown, the ult functioned normally, meaning the bug presents itself only immediately after reconnecting to the game.