The icons will not work if you don't place a special mod_textures.txt in dod/scripts.

To force the icon to display from the disk and not from the .bsp you need to place a reference to EACH icon.

Format is simple. For each icon you add you have a name of the VTF and VMT, a address, a size.

The one below is for dod_churchyard (also older versions too)

		}

		"icon_obj_oak_allies" //******dod_churchyard_b5*******
		{
			"file"	"sprites/obj_icons/dod_churchyard/icon_obj_oak_allies"
			"x"		"0"
			"y"		"0"
			"width"		"64"
			"height"	"64"
		}

How do you get that address and icon?

Mappers use Pakrat to embed the icons in the bsp.
Use pakrat to view the address and extract the VTF and VMT.

Keep it all neat, adjust the icon, then place a reference to it in the mod_textures.txt.

Easy! but a pain.