Twisted Treeline: Minions were invisible

Sorry I don't have a screenshot (I thought alt - prt sc would work) but this one time I was playing Katarina in Twisted Treeline, and then the internet hiccuped or something and I had to disconnect and reconnect.

When I got back on, I saw there was a huge minion wave on the minimap, so I went to go get some juicy farm, and to my suprise, the minions were invisible.

I could still see the little projectiles they shoot, but every minion was intargetable and invisible, and the only way I could attack them is if I used my W, because it's AOE.

Also, before I disconnected I could see the minions fine, and when they were invisible everyone else could see the minions and kill them ;(

Although it was literally impossible to farm we still won :)