We have all seen it. It won't show the callsign until you decode their CQ. If a station is real busy it could take some time before they call CQ. You are seeing them real good but the callsign is <......> . But if you know it is for example KP5/NP3VI do this.
Just type KP5/NP3VI in the "DX Call" window and click "DX Grid" but dont enter anything and they will magically appear in your band activity window without having to wait till WSJT decodes their CQ. Saw this on one of the FT8 Fakebook groups.
73
Mike kb5wbh