Net Carb Chart per Meal?

I have several custom charts, and they are working as expected. I am having difficulty with the Net Carb chart because it has a dropdown for "Group Nutrients by" and the value is set to Day. This is greyed out, but I need this chart to be set to show net carbs per meal. How do I do this? When I download this chart to .xls, it has lumped all the net carb amounts by day, which is completely unusable for my needs. Thank you!