When I install the Splunk ServiceNow Update set the roles are not getting created. I have installed the correct update set for ServiceNow Istanbul release. Other update set components such as the Application and menu options are installing correctly
My S-Now user had correct Admin and Security_admin roles assigned it.
Had to manually create the x_splu2_splunk_ser.Splunk role before applying the update set - seems it is the only way to get this to work