Hello Maljeev. Our company has only one site, hence we don't use this feature. I have checked that all CLIENTS have this field with "Not associated to any site", and all TECHNICIANS have the site field with "Not associated to any site" (I'm translating from Spanish).
From the client form, I infer a certain relation among Sites and Departments, but departments were loaded automatically from Active Directory synchronization, and when I edit them, I see no "Site" related information.
What else may I check to solve this?