This can be caused by a variety of reasons. For example:
The team or neighborhood the person belongs to has no shape (i.e. it has only been placed on the stack of the floor but is not allocated to specific desks in Serraview, which is managed by the Corporate Real Estate team).
Wi-Fi detects the person but does not give a fixed position.
The person is within an exclusion zone on Wi-Fi. When a person is in an exclusion zone the whole floor will highlight. For example, an exclusion zone could be the bathrooms or a server room. For example:
The team or neighborhood the person belongs to has not been blocked to specific desks in the Visual Block and Stack (VBS) module of Serraview. Your System Administrator can correct this by logging into Serraview and editing the team blocking in the VBS.