Lost in the breakout rooms

We have a weekly meeting where I am the host, and I open the breakout rooms and participants go to their assigned rooms for discussion. Sometime I need to escort someone into their assigned room, then I leave and go back to the "lobby." We've done this dozens of times. But tonight, when I escorted some confused participants to their breakout rooms, I could not get out. I could come and go between rooms, but not back to the main page (lobby). The only option was to Close All Rooms, but that nuclear option blows up the whole event.  HELP!