Investigation Request: Matchmaking Error #2 in UEFN

I am developing a game in UEFN and testing it.

I am encountering the following error message:

“Matchmaking Error #2 – There was a problem generating content for this experience.”

There is something that might be related to this issue.
When I checked in from the UEFN editor, a yellow warning error was displayed, but I proceeded with the check-in anyway.

The check-in completed successfully, and it was also reflected in the snapshot history.

Could you please advise on how to investigate the cause and resolve this issue?