Print cells are populating correctly in the Single and Picture Layout but not in the Custom Layout
Be sure you've selected "Custom Package" in the Layout Style menu . It's possible to add addition cells to the "Single Image/Contaxt Sheet" layout BUT it will only you allow you to add one image to one cell. You cannot drag and drop any images to the other cells. There are effectively dead. If that's the case, then go back, select "Custom Package" and add the cells you want.