When Processing a Constituents Query using Revenue-Application Details-Designation-Level 3-Site Record as a Filter, users receive Error: Object reference not set to an instance of an object. The users in question belong to a roll with all Features granted. The Query will process when run by a System Administrator.
Download and install the latest patch, which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.