title: SSRS only displays one row when parameter is used
body: <p>We have an SSRS report that has been running perfectly at multiple sites for over a year.  It calls a MySQL stored procedure and displays the results in a table.  For one particular customer who just migrated to a new server, this report now only shows one row of the results.  It's a row that's early in the results but not necessarily the first row (not sure that has any significance).  Below are steps I have taken so far to troubleshoot.</p>
  
  <ul>
  <li>I've confirmed the procedure should return hundreds of rows by capturing the SQL via the slow query log, and running it directly on MySQL.  So I've ruled out the data, the procedure, and the connection to MySQL.</li>
  <li>This report does have grouping which I thought may be an issue, so I created a new report that calls the same procedure without any grouping and I get the same results.</li>
  <li>As far as we know all other customers are using SQL Server 2008 R2, or 2016.  This customer is using 2014.  We have confirmed this customer does have all the latest SQL Server updates.</li>
  <li>We have many other reports built in a similar way that work for this customer</li>
  <li>We tried replacing the report RDL with another copy thinking it was perhaps corrupt</li>
  </ul>
  
  <p>There has been one thing I've found to get all rows to show up.  If I hard-code all parameters in the dataset, all rows will show up in the table.  If any parameters are passed in (it doesn't matter which ones, or how many), only one row of the results shows up.</p>
  
  <p><strong>Dataset text examples</strong></p>
  
  <p>Displays one row</p>
  
  <pre><code>Call sp_report(?,?)
  </code></pre>
  
  <p>Displays multiple rows</p>
  
  <pre><code>Call sp_report('A','B')
  </code></pre>
  
  <p>These examples both return the same number of rows from MySQL according to the slow query log, but SSRS displays a different number of rows.</p>
  
  <p>Any ideas would be much appreciated.  I've been researching online and conducting many tests to try and figure this one out.</p>
  
  <p><strong>Update 4/16/2019</strong>
  It's been 4 months and we still have not found a resolution for this.  Now some other customers are starting to report this same issues.  It still works for most customers and most reports, but there are a few cases where this occurs.</p>