This is the best information I’ve found regarding the new water system and working with heightmap-generated landscapes. I’ve been searching for these answers for months.
While not perfect, these alternative methods are working great for my project. I’m using the modified brush material method and will probably make a tutorial soon. I’ll be sure to give you a ton of credit. I gave the other methods a try, but modifying those brush materials is the way to go!
Just about everyone using heightmaps seems to be struggling with the water actors, so this information needs to be available via a video tutorial. It will probably be 2 vids: One to explain the problem as you have and highlight examples, and a second with solutions.
I’ll make sure to post the videos here first. Until then, and as D13on said, the “Water System Deep Dive” video from Epic is a must-watch.