In formatting paragraph when no area fill, the first selection of color is ignored if default selected color is used (regardless just clicking OK or clicking the color and pressing OK after). Any other color, i.e. after change the default selection works OK. So to get the default selected color you have to select any other color and confirmed it with OK and then open the menu again and modify the color to any one incl. the previously ignored one works OK.
Thanks for filing. I confirm the issue in 5.0.x. Was OK in 3.6.6.1 > regression. Must have begun with the new background color UI..
*** This bug has been marked as a duplicate of bug 98405 ***