I recently added two gobo zoom 2.0 to my rig, and wanted to display a gobo in 3d view.
Channel 2 is actually rotate gobo, but I changed it to gobo and then selected my png gobo graphic.
Values of channel 2 were from 0 to 255. Gobo would not display.
Gobo would only display when I changed the value of the channel in setup less than full range,
from 1 to 255. It appears that setup wants more than one gobo in the gobo channel.
Image is finished results.