1% corruption left

[Almond Milk]

I started a new world to get the fully purified world achievement, however no matter how much I use the Terraformer to spread the purity, the Dryad always says it's 1%. Do I have to start hardmode to get rid of that last 1%? Or do the Demon Alters/Shadow Orbs count towards corruption. Nothing I've done has helped, I've even looked at Terramap but there aren't any corrupted blocks left. No walls, no ebonstone, no ebonsand, no purple ice, no corrupt grass

[unlucky]

Quit to main menu and enter the world again, then talk to Dryad. I didnt have any problems with this achievement.

[Azuretta]

They aren't counted, and the Druid updates every time you quit off the world and come back, not live.

[Therion ST]

I detonated half my world looking for that damn 1%. No matter what I did, it was still there, until I checked the floating islands. That's all I was missing. I had no idea crimson could reach there. You could try searching there and see if you have luck.