title: Can't access field of document that is visible by printjson
body: <p>this is my first time posting a question here, but I'm out of ideas.</p>
  
  <p>I inherited a very big dataset, that I want to transfer to MongoDB.
  In its simplest collection, it looks like this:</p>
  
  <pre><code>{
      "_id" : ObjectId("57fe2d5d666d9be427d89017"),
      "A_ID" : 1234234,
      "Other_ID" : 1234
  }
  </code></pre>
  
  <p>I did a csv-mongoimport after converting the csv from UCS-2 to UTF-8 with Notepad++ (mongoimport didnt accept UCS-2).</p>
  
  <p>If I query by "Other_ID", I get what I want: </p>
  
  <pre><code>db.getCollection('...').count({Other_ID: 1234})
  -&gt; 26611
  </code></pre>
  
  <p>If I query by B_ID, I dont get what I expect:</p>
  
  <pre><code>db.getCollection('...').count({A_ID: 1234})
  -&gt; 0
  </code></pre>
  
  <p>But if I do:</p>
  
  <pre><code>db.getCollection('...').count({A_ID: null})
  -&gt; 450124
  </code></pre>
  
  <p>We got as far as noticing that the charset is different - loading in Webstorm showed the difference, Notepad++ just started to exhibit strange behaviour (changing fonts in-file, changing font while moving over the text with the cursor,..).</p>
  
  <p>So if I copy and paste the A_ID and do the same query again, it works:</p>
  
  <pre><code>db.getCollection('...').count({A_ID: 1234})
  -&gt; 4
  </code></pre>
  
  <p>I wanted to tell this to the world, I couldn't find anything related to that - and there is a remaining question - how can I normalize my field entries to be in ASCII? 
  Do I have to find those fields and replace them manually with a script? What would be a reliable way to find those fields?</p>