My ReportLibary has 174 reports. When I tried to convert them at once with the Standalone designer, it converted a few of them and threw the following exception (showing part of the Stack Trace):

Application: Telerik.ReportDesigner.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.InvalidOperationException
   at System.Windows.Forms.BindingSource.get_Count()
   ...

Converting the reports in smaller portions was successful.