Strange ending

I have been a lurking reader for some time now and decided to jump into the fray. I am not an umpire but plan to become one after our last daughter graduates high school. I coach a 16U ASA girls fastpitch team. I have learned a great deal from reading the back and forth between you guys.

Anyway, here's the situation. 18U ASA rules. Northern Nationals in St. Louis last week. My daughter's team not playing this game. Bottom of the 8th with bases loaded. 2 outs. BR gets walked. Runner on 3rd is forced home and touches the plate. The BR is getting hugged by the 1st base coach and never reached first base. The offensive team clears the field and goes into the dugout. The defensive team remains on the field and appeals the play because the BR never made it to first base. PU and BU confer and rule that the defense had left the field and therefore the run counts and play is over, even though the defense had clearly NOT left the field as they were still all standing on it.

Again, I have no horse in this race. I just wanted some opinions. I look forward to jumping in threads from time to time, however, I recognize my place here and plan to mostly lurk.

Ed