They same thing happened to one of our players last week. I am pretty sure that there were 17 pairs registered, +allavail+ was in use and yet the tournament started with 16 pairs. I had a call from the pair that were not seated, but was unable to see why they were excluded. I did get a message to say that a different pair had a partner missing, but then the missing player logged in and the tournament started. If there are two or more pairs offline and +allavail+ is in use, do you get a message for each pair?