no Item drops off when combining a Unit with Thiefs Gloves and another item

As seen in the video i linked, I had 2 Cho'Gaths. One on my board with Thief's Gloves and one on my Bench with a Negatron Cloak. When i bought another Cho (during the thiefs gloves animation), they combined to a 2 star cho, but none of items was dropped. So for my next round i had a cho with the 2 temp items from thiefs gloves and the negatron cloak. Next round he got 2 new temp items and then after finishing the dragon round the Thiefs Gloves eventually dropped off cho. I guess this isn't quite how it should work