Landscape Sculpting from Heightmap not painting

Hi,

Have an issue when I’m creating terrain from a imported heightmap file (16bit grayscale png).
I can’t seem to paint values outside of the range from the applied image. There’s a floor and ceiling of how much height I can paint.
I’ve applied the map and want to paint a lake and I can’t sculpt down any further.

Is it possible to work around this, remapping the terrain or doing something other than starting again. I find using the heightmap is a good base to start with.

Have tried 4.7.5 and 4.8 (promoted)

Thanks

My understanding from the docs is that the z height for landscapes is limited to +/- 512 meters, or 51,200 uu. Are you trying to sculpt outside this range?

yeah you’re right. i couldn’t find anything in the docs, must of missed it.
ended up repainting it.