Cards.find() returns no cards

Fooling around with putting together a simple My Cards implementation. However, I cannot get Cards.find() to return any cards. Boards.find() works perfectly.

cards() {
    // return [{ title: 'Card 1' }, { title: 'Card 2' }];
    const query = {
       archived: false,
       assignees: Meteor.userId(),
    };
    return Cards.find(query);
},

Is there something special that needs to be done to get Cards.find() to work?

P.S. Running the query in meteor mongo works perfectly.