Poppy's Ult?

I'm not sure if this has happened to anyone else, but today (March 28th, 2015) I was playing a few games with Poppy and I used Diplomatic Immunity on an enemy support. I did not kill the support, but instead went for a different enemy. However, everyone on their team could damage me, even though my ult was still active. Im not sure if this is a range issue, but I was right next to my chosen target for my ult at the time. This has happened to me twice in the same game, and once in the game before that.