I was trying to mentor one of my friends just now and I received this message:
Does that mean the server had the maximum amount of people it could hold or did it actually mean that he already had someone watching him? My friend also tried to mentor a different player in the same game and received the same message which made me think something was up. Sorry if this isn't a bug/typo!
Means exactly what it says, the server (not the player) has reached the max amount of spectators/mentors.
it means that there is already a lot of mentors/spectators (max is 3 per game I think) in that specific game