title: String not being recognized in pandas dataframe
body: <p>I am trying to find a string in a column in a pandas dataframe and change it to another value, but the string is not being recognized. I cannot figure out why.</p>
  <p>I imported the dataframe from excel and checked excel and see nothing odd there.
  I have tried to copy the text from excel, clear the text in python and type it out directly, and copy and paste from the console - nothing has worked. I have checked for leading or lagging spaces.  I also tried this in a list and used .isin(list) and the same thing happens.</p>
  <p>My code is:</p>
  <pre><code>df.loc[(df['category'] == 'Something - Something Else'),'category']='Changed'
  </code></pre>
  <p>I have other values that are being changed here similar to this one, and they update without issue. Any advice on what else I can try?</p>