Trying to create a water world that doesn't have weird openings into the ground

So I've been experimenting with water only worlds. The main reason for this being so that I can have a world that is just one island with the island being generated through a structure with hopes that stuff like trees will still generate on the island (they do). The problem is that the water only world, whether or not it has the island structure, generates in a weird way where there are weird openings that go down to lava level. The surface rule has been completely overrided with an empty sequence if that's relevant. Could there be any reason for this?