I’m not sure about online gambling, but I can give you an example of offline gambling (B3 / £500 machines): a game called Sphinx Wild. It landed the scatters which awarded £3, then it played 15 free games for zero. So I just received the £3 from the scatter.
I agree that it’s wrong to program a zero bonus into the slot. Instead, any zero bonuses should be implemented as a zero base win instead. By doing that, it’s less of a wind-up for the player.