If a report fails to import, it will be indicated by a red cross. Double-click the entry to open the Details dialog box, which lists details of the error in copying the report. Also, the description field allows only 512 characters. Descriptions longer than 512 characters will be truncated.
Detailed information about the report copying process can be found in the ConversionReport.xml file, in the \SMS\AdminUI\AdminUILog folder on the computer from which you launched the Copy Reports Wizard.