Radio inputs do not group in Polymer

I am using Polymer to build a form dynamically using information received from a server. The server provides a list of elements, where each element may be, for example, a paragraph or a text input or a checkbox. Elements may also be placed into groups. Sometimes a group has a property which specifies that all of the checkbox elements contained within that group should be treated as a single group of radio buttons.

I have a Polymer element which represents checkbox elements. The HTML for the element looks like this:

<span class="paragraph-text language-not-available" hidden="[[textAvailable]]">
<span class="paragraph-text" hidden="[[!textAvailable]]">

The type attribute is assigned to radio when the containing group has the relevant flag and checkbox otherwise. name is normally assigned according to a variable unique to the group containing the radio buttons.

In this case the elements correctly display as radio buttons, but even though they all have the same name, they are not in the same group; i.e. selecting one radio button does not unselect the others. I have tried adding one <form> element that the inputs are all contained within and I have also tried adding one <radiogroup> element that the inputs are all contained within, but neither change affected the behavior.

Ideally I would like the grouping to behave as expected, but an acceptable workaround would be to unselect all the other radio buttons in the element group. So far I haven’t found a way to effectively do this since the data structure which records which elements are members of which groups does not give me a reference to the DOM/Polymer element and I am not familiar enough with Polymer to know how to work around this.