GodBeastX, Ash Darkwood and others recently reported a problem with patch 1.05 where you can no longer set the buy and sell list of item types for stores. Apparently this worked fine in 1.05 beta, but now throws an exception and makes it impossible to set up these lists in 1.05 final.
The bug was reported and acknowledged by Rob McGinnis, Obsidian Community Coordinator.
Check out the thread here:
http://nwn2forums.bioware.com/forums/viewtopic.html?topic=560804&forum=113&sp=0