So, I have been trying to break this, and in the process I managed to have two separate Water Body Ocean actors in scene. For a while it was even in an unloaded cell and was very difficult to delete. Perhaps you have some stray waterbody actors present.
Maybe try to build a new landscape as I did, and see if it occurs again, or re-do yours in a new blank level.
It is very frustrating to say the least. It is still experimental plugin. I was thinking to just add a simple plane single layer water actor for now, and continue with other efforts until some more work is done on this.