This happens because of the way the Django template language does variable lookups. When you try to loop through the dictionaries items,
{% for key, value in confirmlist.items %}
Django first does a dictionary lookup for confirmlist['items']. As this is a defaultdict, an empty list is returned.
It's a cruel gotcha, that I've been stung by as well!
To work around this problem, convert your defaultdict into a dictionary before adding it to the template context.
context['confirmlist'] = dict(confirm_list)
Or, as explained by sebastien trottier in his his answer to a similar question, set
default_factory to None before adding to the template context.
confirm_list.default_factory = None
context['confirmlist'] = confirm_list
