We have implemented the marketplace SDK using the Multiplayer::Lobby namespace that has a breaking bug:
CreateLobby creates a stateless lobby. According to PF staff, they made it sound like it was expected. However, this GitHub doc (Latest commit 4420065 on Dec 16, 2022) proves that this namespace is meant to be stateful; that this is a bug that PF seems to be avoiding.
When will this critical bug be fixed? It's as if this module was outsourced and no one at PF seems to actually know it's even a bug or how to fix it - and, instead, goes with just pushing people to the barely-supported, Mac/Linux-killing, 0-doc OSS SDK that doesn't even support premades for matchmaking (who would want this?).
Related Side Notes:
Either an incomplete function or misleading: The API docs also make it look like events are natively-implemented (like the old, legacy namespaces we don't have access to). Not finding out you require SignalR to use these until you've already implemented it is in pretty poor taste - SignalR being a vastly complex pubsub setup that is completely detached from PlayFab. This is misleading as well that the keyword SignalR is not even listed in here; absolutely 0 indication that a third-party client is required for this. The docs very casually imply that it's native, but it is not.
Another breaking issue: Your docs imply we don't need SignalR if we want to poll, but there's not even a polling option for checking for Matchmaking friend invites to a game.