UE 4.26 Water System and Landscape

Hi, I have a problem that’s somewhat related, so I’m adding my question here, I hope that’s okay.

I have a landscape that won’t get affected by the water system, no matter what. I tried creating new landscapes, it usually works fine, but not on this one (and some others). The spline is positioned on the surface, but the water itself gets generated below it and the terrain doesn’t get terraformed. When I build the level, I get this warning:

“Landscape6_WaterBrushManager_0 This brush requires a Landscape. Add one to the map or remove the brush actor.”

It looks like my landscape is not even considered to be a landscape for some reason? All other landscape systems work perfectly fine with it. Anyone have any ideas…?