World Height really... low?

I’ve been wracking my brain trying to figure this one out. I am using an auto landscape material with world height for things like a snowline, etc. Functionality-wise it’s working as intended. However, the math seems… wrong.

Here are my landscape coords:
image

Nothing too out of the ordinary, I’d hope. This is my current snowline (“Top Material”:

Like I said, working as it should for the most part. However, look at the massive negative amount I have to put in to my instance to get that snowline:

image

-300,000??

Here is my coding - did I screw up the math somehow?

In a nutshell, it’s not that big of an issue as far as the landscape is concerned. However, when I go to add virtual textures to static meshes for auto-blending, it comes a nightmare.

Any suggestions?

The Z of the scale of the landscape defines both Above and Under ground.
Because commonly heightmaps do not start off at 0 as a color.

In all likelyhood, that is why the negative offset.