Zed Ult Shadow Bug

I was playing a custom game as Zed vs Wukong to check my connection. When i first ulted wukong ( i had only a longsword and he had a dorans i was lvl 6 he was lvl 4) i had a massive lagg like 2 seconds long. After the lagg i backed off and 5 minutes later i noticed that my ult shadow did not dissappear, instead it just stood there giving me vision of the area, it even blocked the minions trying to pass by. However it did not mimic my spells it just stood there, i even waited another 10 minutes but it did not vanish, even after i ulted wukong multiple times.

http://www2.pic-upload.de/img/30695365/Screen04.png http://www2.pic-upload.de/img/30695371/Screen07.png