Problems/ Bugs with Ocean

Hello dear community, I have huge Problems with my Ocean.

First of all : I can’t Extend my Ocean Plattform. I know there are 2 Options : “ocean extends” and “Collision Extents”, moving them I can only make the Ocean smaller but not bigger. How can I fix that?

Secondly, I have always under it a hole without mesh as seen in the picture. When removing my spline points the whole ocean dissapears. I Just want a simple Ocean where I can put above a 1vs1 plattform !

Can somebody help ?