No colour picker for customizing labels

we have set up a new site with GVH 2.12 and the options to customize labels and toggle labels are present in the menus and all function as expected with the exception of the color picker. The color picker is hidden (css = display: none) and if I force it to be visible (browser dev console - modify the element's css) it will display and function okay (all colours can be picked and it will show up as the selected colour in the colour swatch) except you cannot apply the change and have it change colour.  Font size, label field and label placement all work fine.

Is this a known issue with the label tool?  Is there some other configuration setting that needs to be checked/changed in order for this to work?