Class visibilities in sheet layer viewports bug? in Troubleshooting Posted September 15, 2016 Michael, thanks - bugsubmit engineer contacted me with the same observation, and when I restarted VW this morning, I'm not seeing the bug either. So it's not a corrupted installation, but some state that is triggered by some as yet unknown event. It does happen, trust me, and I created a new file to upload when I noticed this behavior in a project file I'm working on. So the bug is not related to the file, either, but to some state that is a mystery. Have you, or has anyone else, experienced this? Jim, what is the VGM cache? Not familiar with that. Whatever is going on, it happens frequently.