Sometimes, when the Crocodogs are incoming - there is no sound of the actual Crocodogs (sound wave warning), only the character says someting, like eg. "something is coming".
So after many hours of playing beta, I can definitely tell, that some crocodogs wave warnings are mute.
Eg. one time I knew that the wave should be near (long time have passed since the last one) so I was listening closley - and the crocodogs came without any warning. So definetly something is wrong with this.
Wait till the Crocodog wave and listen. This is a random bug - so repeat if needed.