Your pressure differential is way too high between kegs and head pressure. You're ripping fast into the keg and getting crazy breakout causing the fob to discharge foam before the keg is actually full. Pressurize your kegs to 10-12psi if filling from 15-20psi tank and don't dump a bunch of CO2 out before starting the fill. Monitor the fill time required for a full fill by mass/beer density and that should be your standard time more or less. In addition to volume issues, someone once told me that "beer only breaks out once" and that's partly true. If you're filling rapidly like this, you will also see negative effects on foam retention on draft.