Portalmetrics tracks how many beacons members of your group loot, and how many portals they open with the beacons. This lets you identify who is active and who is leeching. I'm not sure why people would avoid using their beacons, but it happens. The window is hidden unless it sees party members taking part in Sentinax farming.
Use /pm to force the window to open or to re-open after closing it.