Azir bug in nexus siege

I had a match where we killed 15 towers.

There are only 8 towers on the map. That means we killed 7 Azir turrets.

Except the cooldown on Azir's passive is 3 minutes, immune from CDR, and only starts after a turret is destroyed.

7 cooldowns would be 21 minutes, assuming he used one immediately and none of the ones he put up lasted for even a second. The game ends after 20 minutes.

The champion is broken enough in this mode the way he is, so why is his passive letting him put up way more turrets?

Also, please make balistas able to hit inhibitors... teams with lots of waveclear can defend inhibitors for ages. We had all inner turrets by 8min and couldn't finish in 20min because we were stuck on inhibs until around 17min...