I placed barriers and planning around some objects, but in-game, those objects show up black, as if they have no texture (or some other reason). I think it's the barriers that cause this. Could it be I set them up wrong? Is there anything to do with barriers that alters the appearance of objects?

wow never heard of that before (try removing the barriers in ZE and see if there is any change) I assume it's a texture error and I've never heard or seen barriers doing that.

Barriers can't change the appearance of objects. You're most likely missing some textures, or some textures may not have been munged completely/ correctly. Were the objects showing up fine earlier, or is this the first time you've used them ingame in this particular map?

They were fine earlier, and now I added planning and barriers and they show up black (at least in the screen shots from my tester).