I see this a lot as I often drive as neutral support and have a radio (not as an official) to hear. Sometime the officials just screw up. I have tried to get definitions of when to pass in the car for breakaways, when groups are neutralized and so far its the official that decides on the spot.
However prize money is often used as a determiner. If the race is paying 10 deep, then until hearing otherwise you are expected to stay behind 10th place. Similarly if 3 women Pro 1/2 are off there is money at stake. If you were in a position where no money was at stake, that may have affected the decision. Still, sometimes the officials just screw up.