So I was playing around with UE 4.26 water system and a custom height map.
While I managed to place a lake water body in my custom height map (after making sure that every point of the landscape layer is above 0,0,0), I cannot get a river next to it without destroying the offset of the lake. Please see the pictures!
The offset of the lake water body is set to some extreme tiny value so it does not affect the terrain around it. However I cannot switch that off for the river. Placing a river body next to the lake actually somehow connects both of their water bodies in terms of this behaviour and starts carving into my landscape again …
Of course I could just hand sculpt the edges of the lake but I thought, maybe there is something I missed?