First thing to do is to change how you are displaying the stitches on the screen. Instead of displaying as color blocks, try to show them as symbols (or symbols over color blocks). I think you will see the same effect. you appear to have a color defined for that background and that is what you are seeing.
If it is not intended to be a color, you can select it and remove all of that color. That will remove it from the print as well.
First thing to do is to change how you are displaying the stitches on the screen. Instead of displaying as color blocks, try to show them as symbols (or symbols over color blocks). I think you will see the same effect. you appear to have a color defined for that background and that is what you are seeing.
If it is not intended to be a color, you can select it and remove all of that color. That will remove it from the print as well.