This was only working by luck until now. It was "correctly" matching on null online ID (see logic at https://github.com/ppy/osu/blob/abc96057b2cf50e02e0ec939645f6421684495d4/osu.Game/Screens/OnlinePlay/Match/RoomSubScreen.cs#L199-L207). Now it works by actually matching on the online ID.
IStorageResourceProvider
PlayerLoader