title: Django migrations not working with multiple apps
body: <p>I have created a project with django which has 2 apps. Each of them has a models.py that I will show below. The problem occurs when I try to launch:</p>
  <pre><code>python manage.py makemigratios
  </code></pre>
  <p>I get the following error:</p>
  <pre><code>Traceback (most recent call last):
    File &quot;/home/pablo/.local/share/virtualenvs/portfolio-cTVCjELO/lib/python3.8/site-packages/django/db/backends/utils.py&quot;, line 84, in _execute
      return self.cursor.execute(sql, params)
  psycopg2.errors.UndefinedTable: no existe la relación «weatherapi_weatherstation»
  LINE 1: ...gitude&quot;, &quot;weatherapi_weatherstation&quot;.&quot;token&quot; FROM &quot;weatherap...
  </code></pre>
  <p>...</p>
  <pre><code>return self.cursor.execute(sql, params)
  django.db.utils.ProgrammingError: no existe la relación «weatherapi_weatherstation»
  LINE 1: ...gitude&quot;, &quot;weatherapi_weatherstation&quot;.&quot;token&quot; FROM &quot;weatherap...
                                                           ^
  </code></pre>
  <p>The above exception was the direct cause of the following exception:</p>
  <p>They are two very simple models and everything seems to be correct but it is impossible to launch makemigrations. I have also tried to drop the DB but it is still the same.</p>
  <p><strong>Settings.py</strong></p>
  <pre><code> DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.postgresql_psycopg2',
              'NAME': 'portfolio',
              'USER': 'pablo',
              'PASSWORD': '1234',
              'HOST': 'localhost',
              'PORT': '5432',
          }
      }
  </code></pre>
  <p><strong>Models 1:</strong></p>
  <pre><code>from uuid import uuid1
  from django.db import models
  
  
  def generate_uid():
      return uuid1().hex
  
  
  # Create your models here.
  class WeatherStation(models.Model):
      uid = models.CharField(max_length=32, db_index=True, unique=True, default=generate_uid)
      name = models.CharField(max_length=256, default=&quot;No name&quot;)
      created_at = models.DateTimeField(auto_now_add=True)
      latitude = models.FloatField()
      longitude = models.FloatField()
      token = models.CharField(max_length=40, unique=True,)
  
      def __str__(self):
          return self.name
  
  
  class WeatherRecord(models.Model):
      created_at = models.DateTimeField(auto_now_add=True)
      temperature = models.DecimalField(default=None, max_digits=4, decimal_places=2)
      humidity = models.DecimalField(default=None, max_digits=4, decimal_places=2)
      pressure = models.DecimalField(default=None, max_digits=6, decimal_places=2)
      state = models.IntegerField(default=0)
      weather_station = models.ForeignKey(WeatherStation, on_delete=models.CASCADE, default=None)
  
      class Meta:
          ordering = ['-created_at']
  </code></pre>
  <p><strong>Models 2:</strong></p>
  <pre><code>class Post(BaseModel):
      title = models.CharField(max_length=200, verbose_name='Título')
      slug = models.CharField(max_length=200, blank=True, null=True)
      description = models.CharField(max_length=240, null=True, blank=True)
      content = RichTextField(verbose_name='Contenido')
      published_at = models.DateTimeField(default=now, verbose_name='Fecha de publicación')
      image = models.ImageField(verbose_name='Imagen', upload_to='blog', null=True, blank=True)
      author = models.ForeignKey(User, verbose_name='Autor', on_delete=models.CASCADE)
      categories = models.ManyToManyField(Category, verbose_name='Categorias', related_name=&quot;get_posts&quot;)
      url = models.URLField(blank=True, null=True)
  </code></pre>