The Cartoon display modes don't show transparency. The figures with "blank" eyes probably have a transparent layer covering their eyes. This is the case with DAZ's Millennium figures, for instance.

Option 1:

Select each eye.
Display menu --> Element Style --> Texture Shaded

This allows individual body parts to use a different display mode. Transparent materials are indicated by a dotted pattern.

Option 2:

Get rid of the transparent layer somehow. Approaches include the grouping tool and custom morphs. Mazak has morphs to hide the Millennium figures' eyeball layers at his website.