Font Weight missing/not visible Vag Rundshrift D light

Of the four weights of type in the Vag Rundshrift D family I am using light for a client project and today I needed to edit the designs.  However all text in the light weight vanished from the screen when opening the illustrator file.

I have logged in and out of CC, restarted Illustrator and my PC, activated/deactivated the font and or family a couple of times each to no avail.  I have opted to use the light italic for the time being but this is not going to be acceptable to client so need a solution.
The specific font itself appears to be the issue and I am not sure what else could be the matter as I am working in illustrator most of every day and this is the only issue I have on all files associated with this project.  For reference the light font still shows up on InDesign layouts but vanishes when I open in illustrator to edit.