Current implementation is if there is no subclass for a class then it will hide. Which class are you selecting?
Many apologies, I should have tested this more thoroughly before posting. When I was selecting a race (Dwarf for example), the Subrace selection wasn't appearing (for Dwarf, Hill or Mountain). You could still select a subrace if you knew the correct cell, but the cell would appear to remain blank.
Testing this on my desktop, everything worked fine. Went back to my laptop, still the same problem. Checking the Excel versions, it appears I'm running 2007 on the laptop, which I should have checked beforehand. Again, many apologies.