Daemon Icon Bearers have the following ability:
If you roll a 1 when making a battleshock test for a unit that includes aby Icon Bearers, reality blinks and the daemonic horde is bolstered. Add D6 (e.g.) Plaguebearers to the unit.
So I couldn't find anything in the core rules and the GH2017 that indicates that it means you lose no models. Did I miss something or do you gain models when rolling a 1 for battleshock and then lose some models when even a 1 fails your battleshock?