PayPal Express Checkout Not Returning Option Values

PayPal Express checkout is not returning the values of options, at least not in my OpenCart 2.1.1 store running an only slightly modified default installation. Instead, I see an order like--

Awesome T-shirt!
Size: (blank)

Regular PayPal Standard checkout works fine and lets me know, in the orders list, which options were chosen. Otherwise, I just have to guess based on price paid, which is hard to do in some cases.

So I disabled PayPal Express for the time being.

Has anyone else noticed this issue?