Okay, the way you're describing the items being there, then not being visible, but still being present, that sounds like a low memory problem. Switching to wireframe for all the windows should help with that. And when you catch it starting to happen again, close Vue and reboot, then go back to the scene. The inability to texture a group of objects -- or a multi-textured object like a Vue tree -- must be a bug. I just couldn't understand any reason for them to remove that ability deliberately.