No problem. Here’s a janky and unflattering WIP video of my Ocean actor just to help you believe that it can be done. Recording gets a bit choppy halfway through, but it gives you an idea. This map is generated from satellite DEM data for the island of Barbados, processed through Substance Designer and World Machine with respect to my first bit of advice to you about making sure the height map is half above and half below the water line, so that you can stick both the landscape and the water actor at 0 height, and have it line up. And that way the water body feels no need to lose its mind and disappear because its right at the origin, where it apparently likes to be.
Give it another shot, and see if you can get it working. Good luck!