SYMPTOM:
In Strategy Web 9.x and 10.x, consider the following scenario:

CAUSE:
In Web, when exporting to PDF or Excel, a temporary name for the export object is used and then retrieved the server. In this example, the report name is ‘Test (A & B)’. Since the original name of the report contains special characters, it is causing an issue with Single Sign-On session state.
ACTION:
Re-name the report name and remove the special characters