YSFlight: Can't disable ground texture

• YSFlight version: 20181124 (stable)
• OS: Linux, x86_64 (Debian 9.x)

Actual behavior

Disabling «Option(0) > Config (C) > OpenGL > Use Ground Texture» NOT works — ground texture always used for all sceneries in game:

Expected behavior

Disabling«Use Ground Texture» should work as expected.

In YSFlight 20150425 this work as expected.