Django-table wrong output

Question

I have django model:

class Sessions(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey('Users', on_delete=models.CASCADE, related_name='user')
    session_start = models.DateTimeField()
    last_confirmation = models.DateTimeField(null=True)
    error_status = models.CharField(max_length=50, default="Lost connection.", null=True)
    session_end = models.DateTimeField(null=True)
    status = models.CharField(null=True, max_length=1)

And I have a view function which must return QuerySet with three columns ( 'session_start','last_confirmation',differenc_time ('last_confirmation' - 'session_start'):

def user_home(request):

    info = Sessions.objects.filter(user=request.user.id).annotate(
        time_difference=ExpressionWrapper(
            F('last_confirmation') - F('session_start'),
            output_field=fields.DurationField()
        )
    ).values('last_confirmation', 'session_start', 'time_difference')

    return render(request, 'home_user.html',
                  context={'data': info})

But in browser i get all columns: