title: Django admin list_display not showing several objects
body: <p>I have just begun to play around with Django admin views, and to start off, I am trying to do something very simple: showing several fields in the listing of objects using list_display as explained here: <a href="https://docs.djangoproject.com/en/dev/ref/contrib/admin/" rel="noreferrer">https://docs.djangoproject.com/en/dev/ref/contrib/admin/</a></p>
  
  <p>This is my dead simple code:</p>
  
  <pre><code>class ArticleAdmin(admin.ModelAdmin):
       list_display = ('title', 'category')
  </code></pre>
  
  <p>Unfortunately, the list_display option is causing the columnar view to appear, but only some of the objects (40 out of 85) are now displaying in the listing. I cannot deduce why certain objects are showing over the others - their fields look like they are filled similarly. It's clearly not paginating, because when I tried it on an admin of another model, it showed only 2 objects out of about 70 objects.</p>
  
  <p>What might be going on here?</p>
  
  <p><strong>[UPDATE]</strong> Article Model:</p>
  
  <pre><code>class Article(models.Model):
      revision = models.ForeignKey('ArticleRevision', related_name="current_revision")
      category = models.ForeignKey('meta.Category')
      language = models.ForeignKey('meta.Language', default=get_default_language)
      created = models.DateTimeField(auto_now_add=True, editable=False)
      changed = models.DateTimeField(auto_now=True, editable=False)
      title = models.CharField(max_length=256)
      resources = models.ManyToManyField('oer.Resource', blank=True)
      image = models.ManyToManyField('media.Image', blank=True)
      views = models.IntegerField(editable=False, default=0)
      license = models.ForeignKey('license.License', default=get_default_license)
      slug = models.SlugField(max_length=256)
      difficulty = models.PositiveIntegerField(editable=True, default=0)
      published = models.NullBooleanField()
      citation = models.CharField(max_length=1024, blank=True, null=True)
  </code></pre>
  
  <p>Before adding list_display:</p>
  
  <p><img src="https://i.stack.imgur.com/pQ7P3.png" alt="Django amdin before list_display"></p>
  
  <p>After adding list_display:</p>
  
  <p><img src="https://i.stack.imgur.com/6XY2r.png" alt="Django amdin after list_display"></p>
  
  <p><strong>[UPDATE]</strong> This behaviour occurs only when ForeignKey fields are included in list_display tuple. Any of them.</p>
  
  <p><strong>[UPDATE]</strong> Category model code:</p>
  
  <pre><code>class Category(models.Model):
      title = models.CharField(max_length=256)
      parent = models.ForeignKey('self')
      project = models.NullBooleanField(default=False)
      created = models.DateTimeField(auto_now_add=True, editable=False)
      slug = models.SlugField(max_length=256, blank=True)
  
      def __unicode__(self):
          return self.title
  </code></pre>