Scale of ingame custom scenery is x1000 bigger

[HexHyte]

The in-game scale of the imported scenery is 1000 times bigger than normal:

Using a 0.001 scale in the Gizmo window of the scenery editor fixes this issue.

I suspect that the Blender "Unit Scale" and "Length" values play a role in this process, but it is unclear what the correct values should be, as setting them to "Meter" and "1.000" does not resolve the problem.