It appears that there is no default list for the Stock Type entry, but no big deal, it's easily added. This is not a surprise (to me), really, because the desired stock type needs vary from one business to another. What one business might call a certain 'stock type' may not be the same as another's.
So what I did first:
Same screen with the link to the inventory categories maintenance, in the middle section, there is a link near the bottom of that section called: Maintain stock types
At the stock type screen, I entered R for type, and Resistor for the type name.
my stock type entry
Then back to the categories to add what you did:
my category entry