On latest PTR build changed ActionBarActionButtonMixin.
Now Blizzard use ActionBarActionButtonDerivedMixin Gethe/wow-ui-source@9e8c71b#diff-b1cfbbf99c2cbb68ef9f30e85812e5a736154dec48da4d5ff2ed082c6e89c54eL91
Need to change all hook ActionBarActionButtonMixin to ActionBarActionButtonDerivedMixin. Without that color not worked on PTR.

For me, color not worked on PTR until I manually change mixin to new one.

We should be okay for the moment. As far as I can tell, the entire point of that mixin is to define OnDragStop as a function that does nothing.

ActionBarActionButtonDerivedMixin = CreateFromMixins(ActionBarActionButtonMixin);
function ActionBarActionButtonDerivedMixin:OnDragStop() end 

in tullaRange, we hook the OnLoad event from ActionBarActionButtonMixin

local f = EnumerateFrames()

while f do
	if f.OnLoad == ActionBarActionButtonMixin.OnLoad then
		actionButton_OnLoad(f)
	end

	f = EnumerateFrames(f)
end

-- grab later ones, too
hooksecurefunc(ActionBarActionButtonMixin, "OnLoad", actionButton_OnLoad)

Because ActionBarActionButtonDerivedMixin doesn't redefine OnLoad, the code should still work as expected.

10.1.0-beta1

With mixin change: