Popup.open() not working

Having trouble getting the popup to open for a sort selection.

From myCards.jade

template(name="myCardsSortPopup")
  ul.pop-over-list
    li
      //with "my-cards-sort-board"
      a.js-my-cards-sort-board
        i.fa.fa-th-large.colorful
        | {{_ 'my-cards-sort-board'}}
        if $eq Utils.myCardsSort "board"
          i.fa.fa-check
    li
      //with "my-cards-sort-dueat"
      a.js-my-cards-sort-dueat
        i.fa.fa-calendar.colorful
        | {{_ 'my-cards-sort-dueat'}}
        if $eq Utils.myCardsSort "dueAt"
          i.fa.fa-check

From myCards.js

  events() {
    return [
      {
        'click .js-toggle-my-cards-choose-sort'() {
          Popup.open('myCardsSortPopup');
          // eslint-disable-next-line no-console
          console.log('open sort');
        },
      },
    ];
  },

I can see the 'open sort' in the console so the event is getting called, but the popup does not open.

Any thoughts on what I am doing wrong?