We use GetTexture to check if a layout has set a texture on an element or sub-widgets, which worked fine with SetColorTexture up until 8.1. Now it returns nil, and there is no way for us to check whether the layout has set a color texture or not. If SetColorTexture is used on an element or sub-widget that an element can control, the Enable method of the element will set the default texture instead.

As a temporary fix we urge layouts to use SetTexture with a blank texture (e.g. "Interface\ChatFrame\ChatFrameBackground") and then use SetVertexColor to change the color applied to it, until this has been resolved on Blizzard's end.

Should be solved in the next patch, on the PTR GetTexture returns "FileData ID 0" instead of nil when SetColorTexture is called.