Ember template - failed to execute 'createElement' on 'Document': The tag name provided is not a valid name

I have 2 models loaded into my route and am trying to render a component for each into the same template as below:

{{#each fav in favs}}
  {{user-fav fav=fav}}
{{/each}}
{{#each tag in tags}}
  {{user-tag tag=tag}}
{{/each}}

The favs models load fine but the tags gives an error : 'Failed to execute 'createElement' on 'Document': The tag name provided ('telegram-client@model:tag::ember763:JavaScript') is not a valid name.'

If I remove the {{user-tag}} component and insert the HTML its fine and all tags are rendered.

I presume this a bug in HTMLbars and I'm going to update Ember-cli eventually (I'm using v0.2.3) but any other advice much appreciated.