UpdateSession doesn't reduce number of players (NumOpenPublicConnections). C++

I call UpdateSession in PostLogin and Logout to refresh the session stats but when a player leaves the number (NumOpenPublicConnections) doesn’t change? It seems to go up when players join though, any idea why?

This is with OnlineSubsystemSteam (not SteamSockets). Listen servers. UE4.27. Internet sessions.