Product With Single 'variation', Not Showing That Variation

For example.

We have a t-shirt which is currently only available in XXL and BLACK. Maybe other sizes will be added in the future, maybe not.

Anyway, i create that product. Go to Variations, add it in XXL and BLACK and save it.
Product shows up fine, but nowhere on that product it shows that it's an XXL and BLACK.

The buttons for the variations are missing.

Even tho it's only available in XXL and BLACK i want to see that on the product page.
How to get this to work?