Just a quick note in case someone else hits this issue.
I updated from VW15 to VW16 and found my solar animations didn't show shadows in OpenGL renders. I checked and the issue was persistent across both an iMac and MacBook Pro.
The solution I finally found was to delete the Heliodon that was in the model (created in the earlier VW) and replace it with a new one after recording the compass setting etc. All shadows appear to be now working.
cheers
Bruce