If you have a drilldown portlet on a project dashboard, you cannot export all data via "Export to Excel" or "Export to PowerPoint".
These drilldown portlet export options will export an almost empty document (only the column name row is exported).
This issue is caused by DE34093.
Sustaining Engineering has fixed DE34093 in CA PPM v15.4.
Use "Export to Excel (Data Only)" export option instead as it is not affected.