Default sorting not working: sortFunc not called for defaultSortName column

I have too much code to show it all, but its basically like the "Custom Sort with Extra Data" example. Only I want to sort on the "Product Quality" column by default. In my options I have basically:

Object.assign( options, {
defaultSortName : 'quality',
defaultSortOrder: 'asc'
} );

I stop in Chrome debugger and see the options being set. But I still always sort on the first column. Only when I click on the header to sort on the "Product Quality" column do I stop in my sortFunc -- it works then so I know the problem isn't with the sortFunc itself.

Any thoughts?
-= Jab