Opacity not working for me

Operating system: Ubuntu 18.04.1 running in VBox on Windows 10
Slicer version: 4.8.1
Expected behavior: Opacity should work
Actual behavior: Trying to follow the 4 min tutorial. Works well until setting the opacity for skin. Just doesn’t work. As far as I can tell, am following correctly with skin model selected. I don’t see an apply button or anything to actuate the choices.

You can set the opacity for a model in two ways:

  1. Double click the opacity (1.00) in the tree view. Then a slider appears moving which you cahange the opacity
  2. Use opacity slider in the 3D Display section
    Neither needs an apply, just moving the slider.