Colourised items appearing too dark (sometimes)

So I have some white icons (#FFFFFFFF) that are colourised using a global variable.

When I copy one of those icons it appears correctly in the preview window, but much too dark on the home screen. I have another item (a white PNG) that is colourised using a different global variable colour and it too is appearing too dark.

The same occurs no matter if I recreate the object and colourise it or if I copy an existing colourised object. Something is broken with the colourising filter. Al least in my current klwp file.