Gameplay - Lulu Bug

In one game, my Lulu's polymorph failed me twice. One instance occurred when Bard was coming in to lock us down. From a hidden bush, I polymorphed Bard, and to my surprise, he got off his attack (while under polymorph) and locked both me and my Carry down. The second instance occurred in a teamfight which included an opposing Yasuo . Immediately after Yasuo cast his wind current at my team, I polymorphed him to deny his ability to ult. Not even a second later, he combo'd with his ult onto my airborne allies (talk about a deadly squirrel still capable of slicing up my team).