Symptoms

K2 Workspace is not allowing access to the K2 Workspace menus even though they have been added to the Security Settings. In fact, only the K2 Service account can see the menus.
 

Diagnoses

Discovered the customer very recently upgraded K2 and has two domains. K2 Workspace correctly showed both domains in the Management Console User Managers section. Opened the web.config file from Program Files (x86) > K2 blackpearl > Workspace > Site and searched for "LDAP". Found only the primary domain and not the second domain.
 

Resolution

Added the second domain to the web.config file.