When you set the collision to “use complex as simple” (in the static mesh editor) everything should work fine (from the water plane beneath the waves).
Some months ago I have seen a thread about the same problem -> currently searching for it
I have tried many different collisions (in the mesh editor) and applied them to the SM_FloorPlane, but nothing works. I can’t locate “use complex for simple” anywhere in the mesh editor. Is it in a menu, an icon, or somewhere in the details tab?
Just search for “collision” in the search bar and then choose the collision complexity -> https://www.youtube.com/watch?v=TTsAYpqHU-c (3rd way). But when you just want to have a water simulation, do what Havoc suggested