title: Magento 2: Product import does not create sub categories
body: <p>I'm importing products from a CSV-file. The categories-column of the import file has a value like this:</p>
  
  <pre><code>Store Amsterdam/Lunchbox;Store Amsterdam/Lunchbox/Hot Sandwiches
  </code></pre>
  
  <p>I've set ";" as a <em>Multiple value separator</em> in the Magento 2 import settings.</p>
  
  <p>Somehow Magento only adds the <em>Store Amsterdam</em> (root) categorie and imports 0 products (Probably because it doesn't reach the destination category).</p>
  
  <p>When I create the sub categories by hand all products import correctly. But I don't want to do this for every 34 remaining stores.</p>
  
  <p>In the report it says: <code>Category "Store Amsterdam/Lunchbox" has not been created. URL key for specified store already exists.</code></p>
  
  <p>What is going wrong here? Maybe writing permissions on category table? Different Magento user?</p>