I don't know why the default ground plane was having issues. But I was able to get ground plane HR (high resolution) to work. And as some above pointed out the changes are revealed upon render not preview. I was a bit confused about the "one sided square", I searched for that but found nothing, I opened Blender and stretched out a box to look like a large ground plane then added a material color to top plane. I sadly didn't have much look with that in Poser. Maybe I should have used UV mapper also and not just a material color for a plane? I just did that so Poser could see that side when I exported the obj.