Matchmaking with Epic Online Services

Hello wise people,
In our Unity 6 multiplayer project, we use Normcore + Matchmaking from the Epic Online Services. When connecting users to a multiplayer game with each other using Matchmaking, and under certain circumstances that are not fully understood, so-called "free sessions" (ghost sessions without the players) can sometimes be created on the server. This usually happens when players leave the room because of unknown reason. The session doesn't immediately close when the room is empty, but it still has a duration and a broadcast period (broadcast time: about 5 minutes, duration: about 10 minutes). This could be manually triggered during testing by disconnecting the internet or crashing the project from the Unity editor.
Matchmaking works correctly until these ghost sessions occur. Once they occur, no player can join any newly created sessions. Only after waiting a full 10 minutes, when all ghost sessions have disappeared, everything return to normal.
Has anyone encountered this problem, and if so, how did you resolve it? The Epic Online Services SDK is limited in its settings for Unity.