DS.attr() isn't marked dirty, can't rollback

I'm using a DS.attr() data type in one of my Ember-Data models (note, no attribute type specified) to allow me to store nested JSON data. For the most part, it works fine, however, when I make changes (e.g. with an input bound to one of its properties) the record isn't marked as 'modified' in the Ember inspector, although the view bindings are all working properly (i.e. if I echo the same property as text, it changes when the input changes). Similarly, after making a change to one of these properties, if I call the rollback() function on the model, the data isn't rolled back.

Of course, the regular properties work just fine, so I'm assuming this has something to do with the DS.attr() type not being specified.

Is there a way to make this work efficiently? I would try to use embedded records, but this data doesn't use any record IDs.

Thanks