Black areas map bug?

Is it something different here or is it a map bug? I already broke both sigils in this region and my map still stay black on many paths I visited. How to deal with it?

https://preview.redd.it/tdtfwbnbz7ug1.png?width=2010&format=png&auto=webp&s=d538bf8043efbb7b0fd5ea170b08960304abc620