I’m afraid CS has no involvement with the Beta or Stress Test process, Daveros, so we aren’t really able to provide official information. However, there is a note here that shows the removal of stress test access, and indicating that this was a mass action, so it doesn’t look like a bug.
The post by Bornakk indicated that they were unable to accomplish what they wanted to and those who were invited to the first stress test would be able to participate in the one on the May 29th. It was likely just for that period and new invites will be sent out for the next one in June.