logged on user is not shown or searchable

We search devices in connectwise control with function "search-by-user-shortname".

For example: my samAccountName-user in Active Directory is "bnan". When i type this string into search, i find every device i'm currently logged on. But at about 30-40% of our devices this field isn't filled even thought the user is currently logged on. Is this a bug or is there another situation, this can happen?