Why didn't Iono work?

MPloch

Hello, I played iono as the last card in my hand and my opponent still had cards in their hand, but Iono did not activate to make them shuffle their hand and neither of us drew cards. The card says it should work if EITHER player puts cards on the bottom of the deck they both draw the number of cards equal to their prize cards.

TechHog

Did they have Milotic (Rapid Strike) in play? That would prevent the opponent from shuffling their hand.