title: Data Flow left outer Join results in empty data set when executed, but not on debuging
body: <p>We have a Left outer join configured between two data sets. When executed, the Join shows no results, although when debugging it does. Both dataset of the join contains data and the condition is fulfilled, although with a left outer join I would expect at least the content from the first data set.</p>
  <p><a href="https://i.stack.imgur.com/9nJNk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9nJNk.png" alt="enter image description here" /></a></p>
  <p>The dataflow pipeline contains two similar joins and in both we have the same behavior.</p>
  <p>The datasets involved in the join contains from 20K to 60K records. However, the flow loads a couple of datasets around 1 million records. We would expect some error if this was related to memory though...</p>