I'm having a problem with NodeGroups in materials not working. I made new file to test it (attached), to make sure the problem wasn't with the file I was working on.
If I'm in Rendered View/Interactive Mode and create a group of some nodes in a material, the viewport won't update and the status stays at "Waiting for image...".
It doesn't update if I make changes to the shader etc in the group (not until I ungroup the node group). If I zoom, pan etc the Viewport will update, but with the material as it was before creating the node group.
If I then update the scene (or stop/start the rendered view), or do render the image, that node group will appear as an white diffuse (standard/unassigned material), even if I use mix nodes etc.
I've looked at the logs and can't see any messages that differ from before I create the node group to after.
Screencast showing the problem: https://drive.google.com/file/d/1w6AqgP ... sp=sharing
A. Windows 10
B. GTX 1080 - 8GB
F. 4.00 v16.3
G. Blender 2.79b