WooCommerce Composite Products Variable Product Dropdown Not Displaying Options

WordPress 4.5 WooCommerce Version: 2.5.5 WooCommerce Composite Products Version: 3.6.3

I'm making a "variable" product. I expect that if I define two attributes (Natural gas and LP gas), and check the "Used for variations" box, and then in the Variations tab I see the two new attributes listed variations, that these should appear in the product page dropdown for "Gas type". Instead, I see Gas type with a select box dropdown, which says "choose an option", but when I click "choose and option", the select box dropdown doesn't have any of the options or variations I created in the Edit Product page.

via Chebli Mohamed