Symptoms
Assume that you have a Microsoft SQL Server 2012 Reporting Services (SSRS 2012) or an SSRS 2014 report that has a tablix that will return an empty dataset, and you set the "NoHeader" attribute in the RsReportServer.config file for CSV rendering. In this situation, when you export the report to CSV format, the .csv file contains field separators.
Note The expected behavior is that the CSV output is blank as it was in the earlier versions of SSRS.Resolution
This issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 1 for SQL Server 2014 SP1 /en-us/help/3067839
Cumulative Update 6 for SQL Server 2014 /en-us/help/3031047
Cumulative Update 3 for SQL Server 2012 SP2 /en-us/help/3002049
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.