I have the same issue. Tiles nearer to the camera are culled and I can see things underneath.
Looking in the distance, or at the right angle and it’s all purty:
Look down, get closer, etc, the right (wrong) spots and it clips. I didn’t make any adjustments to the water parms, I only dragged it into the level and added 4 pts to the spline to make it fit behind the landscape:
No idea. I tried making the clipping-plane closer/farther away, no diff. Rebuilt virtual textures, streaming textures, entire level w/lighting, closed, rebooted, reopened; nada…dafaq