This is something that I am very interested in as well. I cannot seem to get the group masters to "flash" any intensity when they are at 0 . I have attached screencaptures.
Group masters behave like an inhibitive submaster on a traditional theatrical console. For them to work, you need to bring the intensity to a non-zero value. So, record a list with the desired intensities at full, and play it back on a virtual master.
