Actually that IS where the problem arises. Thanks for thinking of that question. I AM in fact attempting (and failing) to delete them in Block Manager. Sorry I wasn’t clearer about that. I haven’t had any trouble deleting them from the model.
I guess I should purge the materials. Those are legacies from the previous project from which this one was started. I have a string going about ensuring that I can do such things thoroughly. (Purging and Deleting Redundant Elements - #16 by pascal)