I'm not sure if this is the exact same issue, but I found any items in slot 57 and above can not be interacted with in trade windows but can be interacted with in inventory windows.

Edit: Disregard the slot number. I tried a different game save and that number had no relevance and I could interact with everything. Not sure what is wrong with the current game.

Last edited by dakkai; 23/01/14 10:12 AM.