I just experienced three different (but related) bugs in one game of Tarkir: Dragonstorm Quick Draft.
First, my opponent had tapped down my Equilibrium Adept with a Ringing Strike Mastery, so I cast Ureni's Rebuff to return my own creature to my hand. The enchantment went into the graveyard, but my creature stayed tapped on the battlefield; it still wouldn't untap on my untap step, and I couldn't pay 5 to untap it.
Later in the same game, I cast Riverwalk Technique to bounce a Dirgur Island Dragon (paying 2 for the Ward), and again the creature didn't return to my opponent's hand. Strangely enough, it seemed to just sit on the battlefield without the flying animation and without the Ward graphical decoration, and my opponent didn't appear to be able to attack or block with it.
A short while later, I cast my Ureni's Rebuff again from the graveyard to try to return another Dirgur Island Dragon to my opponent's hand (again, paying the 2 cost for Ward), but it didn't leave the battlefield, and this time my opponent was still able to attack with it... and they ended up winning the game hitting me with it.