johnbgardner posted this warning to other builders in the official forums:
I just noticed that when you convert an environmental object back to placeable the Current Hit Points, Hardness, and Hit Points are left at 0. Believe it or not this makes the placeable unuseable regardless of the Useable setting. It was driving me crazy that one placeable could be used while another with identical properties (except for the above which I had ignored) wouldn't. Setting those properties back to the default values made the object useable again. Wierd.
See the thread here:
http://nwn2forums.bioware.com/forums/viewtopic.html?topic=535748&forum=1...