Barron buff doesn't get applied to minions who took poppy's ultimate

I was watching the 2016 LOL world championship group stage between IMay(blue) and SKT(red). Around between 30 min. and 31 min., SKT was attacking the bottom inhibitor tower. The blue team top lane champion poppy used her ultimate to SKT's champions (2?) and a couple of minions, and they got knocked back. After that, the minions joined back to the bot lane, but at that point, they didn't have the barron buff. I think the barron buff was still in effect, as I saw the other minions with the barron buff.