Why does my P&L report only pull from one category when all are selected?

For an income or expense category to show up under Business you have to assign it a Schedule C tax line number. Go into Edit Category and assign it one.  

If you need to see a schedule C, here's the blank form….

You can either assign the tax line number to an existing category or you might want to set up a new category for it to keep the existing one under personal if you have the same expense for both personal and business.

To check the tax line assignment open the Category list by either clicking on the Category Icon or go to Tools-Category List or Ctrl+Shift+C.  Then select the category and right click on it to Edit it.  Click on the Tax Reporting Tab and check the box for Tax related and pick a Schedule C: tax line item.