You are logged in to the Notification Server console with an account other than the Symantec Administrator and are loading a report that you've previously used successfully. The report contains a filter parameter selector as a drop-down menu but, when clicking the selector, no drop-down list appears and you are unable to run the report without one.
The report will attempt to load the last filter that was selected by the logged in user. In this case that filter has been deleted by an administrator. This will cause the filter menu parameter to lock-out and no other ones can be selected, even if the user has rights to see other filters.
A permanent fix is available ITMS 8.1 RU4 (Release Update). Upgrade using DOC10690
As a Symantec Administrator: