That might be the Gloves in the cart in the Druid Grove near Doni the mute Tiefling kid.
I even tried thunder arrow on it. Not Thunderwave yet. But worth a try to get them out of the cart
Thieving such form Dammon the Smith is much easier in Patch 5 then getting those glued ones in the cart.
I can move the box sitting next to the cart onto the cart, and that box can still be opened.
But the box that was on the cart from the beginning, and the gloves next to it, that are now lying beside the box I threw into the cart remain unreachable. Pffff.....
So it' does not seem to be position related but object related.