WowAce

in the settings you can set the color for how you want the MUF to look when a unit is afflicted but can also change an alpha setting.  the color works but alpha does not. 

dunno if it will help bugfind, but I hamfisted a workaround by manually setting alpha in Dcr_DebuffsFrame.lua

-- set the status according to RangeStatus
if (not RangeStatus or RangeStatus == 0) then
Alpha = 0.3;
self.UnitStatus = AFFLICTED_NIR;
else
Alpha = 1; 

Alpha = 0.3;
self.UnitStatus = AFFLICTED;
BorderAlpha = 1;
end

yeah the alpha is part of the color picker UI but I'm not sure it was meant to work as you want... alpha is supposed to be at 1 when the unit is in range.