Terminate game session

Hello guys! I'm kinda new to Gamelift for Unreal Engine and I'm using eeldev plugin. It's working great but now I'm having a problem. For example, in some cases when someone creates a new game session and suddenly decides to leave without joining the session, that session will remain empty and active. What I want to do is to check every 2-3 minutes if the server is empty and destroy it after 2 minutes (in case it's empty). This is what I've done but it's crashing the session.

I also have another question. I'm using StartMatchmaking to search/create a game session. After the ticket is in queued, I use DescribeMatchmaking to get the status of the ticket. What I want, is to display the matched players but this is showing only if the matchmaking result is completed (which it's after 10-15 seconds). Is this the time it takes to match multiple players? Even if I started the game at the same time? I get the players from DescribeMatchmaking, using the game session arn -> Describe Player Session. Thank you!