CuiImageComponent Sprite Doesn't Work?

As per this part in RustCUI for CuiImageComponent:

Code:

[DefaultValue("Assets/Content/UI/UI.Background.Tile.psd")]
[JsonProperty("sprite")]
public string Sprite { get; set; } = "Assets/Content/UI/UI.Background.Tile.psd";
[DefaultValue("Assets/Icons/IconMaterial.mat")]
[JsonProperty("material")]
public string Material { get; set; } = "Assets/Icons/IconMaterial.mat";

I want to add that texture to used all over Rust's UI to my Cui because at the moment it is just a solid colour. It used to have a texture, but at some point in the past year that has changed?

 

I've just inspected Rust\Bundles\shared\content.bundle and found those assets within it, so why doesn't it give the texture when used? I can clearly see the texture in the image.

 

Doooes anyone have any ideas?