Matchmaking - "Steam ID is invalid"

[Tzook]

Hi,
I'm using the latest greenworks with steamsdk 1.51.
I can create lobbies successfully, getting the lobby id back (e.g. "30758872145812812").

The problem is when I try to do any action after creating that lobby, I get the error "Steam ID is invalid".
Example:
greenworks.getNumLobbyMembers(steamLobbyId)
greenworks.joinLobby(steamLobbyId)
greenworks.leaveLobby(steamLobbyId)

When I run "greenworks.getLobbyByIndex(0)", I get an empty object.

Any help?