Nothing happens on succesfully joining a matchmaking session

Hello, I've implemented a simple multiplayer experience with two levels, an empty level that serves the purpose of a lobby, where a user can choose between creating a matchmaking session, viewing available matchmaking sessions and joining a matchmaking session.

Creating a matchmaking session works, and after succesfully creating one, the player is transported to the second level where multiplayer gameplay is supposed to happen.

Second user can view the session and its ID, but when I use the join session blueprint node, the On Success pin fires yet nothing happens.

Oculus analytics info displays that matchmaking sessions are created but canceled after 40 seconds (which is the time I generally wait to see if something happens).

Any help would be appreciated