Cleared a blighted and blight-ravaged map... atlas icon for blighted lands is still glowing blue

I don't understand this. Every other map/area once cleared loses that blue glow that, I assumed, indicated it hadnt been completed yet. Is there something more I need to do to clear that glow (it is irking me in my attempts to properly 'complete' my atlas), or is this just another one of the 'things?'

I've noticed this as well. A minor annoyance, but an annoyance to be sure.