Gallery example ComboBox doesn't drop down

Clicking on the "Paris" ComboBox in the gallery example under the Styles tab does not cause the items to drop down. The issue is only present with the example; other uses of ComboBox work:

import QtQuick 2.0
import QtQuick.Controls 1.0

Rectangle {
    ComboBox {
        anchors.centerIn: parent
        model: [ "Banana", "Apple", "Coconut" ]
    }
}

There is also a warning printed than can be reproduced with any ComboBox:

No suitable 'textRole' found for ComboBox.

There is a small grey rectangle drawn at the bottom left corner of the ComboBox that was not captured by the screenshot, which is presumably a small portion of the drop down itself.