Caption cues don't render in custom element as expected

[weboverhauls]

I'm using the appendCueCanvasTo option parameter in order to render the captions there. But it's just rendering to default upper-left position. My init JS:

var videoCaptions = document.getElementById('videoCaptions');
captionator.captionify(null,null,{
    "appendCueCanvasTo": "videoCaptions"
    }
);