@2nd image' chamfer that vertex. youl get a equaly spaced square, then use a bridge between corners and in the middle reform it into a square instead of a [x]
whats an interactive viewport? what was it before? hoping that includes mo post process shader support, nicer shadows and Direct X intergrated into viewports?
I think this is a limitation of skeletal meshes. Not just actor X. You could try using FBX or collada. http://udn.epicgames.com/Three/FBXImporterUserGuide.html