[GAMEPLAY] Heimer Turret Won't Attack Nexus if Enemies are Nearby

I unfortunately lost a ranked game just now while rushing the enemy Nexus after a barely won Baron fight. Had my Heimerdinger turrets attacked the Nexus, we would have won the game. They didn't and we lost. The tooltip for Heimer on the wiki states:

> Turrets have short-ranged basic attacks, prioritizing Heimerdinger's attack target if within range and then the closest enemy.

It doesn't say the target has to be a champion, the Nexus should count, and if I'm attacking it to try and end the game, my turrets should as well. Here is a video uploaded to my Youtube channel to showcase how this impacted the game

https://www.youtube.com/watch?v=9bS3SmI9AhY&feature=youtu.be