Swiss tournament truncation

I got this back from Chess.com re the cutting off of the last round of our 5 round Swiss, which coincidentally happened again last night 

A Swiss tournament may be shorted if players disconnect or withdraw. Is it possible that one player withdrew before the final (5th round) should have started? The maximum rounds for a player pool of 9 players would be four, so that may have happened in this case.

A tournament may also be shortened if no adequate pairing was available according to these guidelines:

1. Pair players with the most similar score throughout subsequent rounds
2. Don't pair the same players more than once
3. Avoid the same player playing the same color consecutively (never three times in a row)
4. Possibility for at most one undefeated player at the end of the tournament