mens slow pitch softball ruling

Question
there is a runner on third and first bases with one out when the batter hits a fly ball to center field which is caught and is then thrown to the first baseman forcing out the runner on first as he returns to first base after the catch for the third out. the runner on third tags up and after the catch runs home crossing the plate before the play at first is completed. does this run count? our volunteer umpire said it did but we did not due to the third out coming on the force back at first. please advise who is correct.
thanks for your help

Answer
Harold,

Even thought this isn't a fastpitch question, which is my area, I am certain this situation would be handled the same in all of softball land.

The runner that was doubled off of first was not a force play.  It was a live ball appeal of a runner leaving the base prior to the ball being caught.  This and the runner scoring from third is a timing play.  Whatever happens first, happens first.

The appeal play doesn't negate the run if the run scored before the appeal play.

The run counts!