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?'