how does sort in views handle fields with multiple values

I am troubleshooting a view that is supposed to produce listings in alphabetical order by a certain field. Right now, I am getting listings ordered by nid instead.

I think the problem is this: The sort-by field is defined as having multiple possible values. (In reality, it has two values; the first [0]['value'] is what is supposed to get sorted on.) What does sort do in such a situation?

Thanks!