Weird box brush subtraction without reason

I have this annoying problem that i cant get past. When i put brush box on the level there is this weird shaped area where it subtracts my brush so i cant place it where i need to. I went trough all my actors in world liner to see if i have any subtractive brush there but no. Does somebody know what may be causing this or give any hints what i am supposed to bee looking for or is there any common setting that can do this.