Creating new border style changes formatting

In calc, I have selected a 3x6 set if cells. I have a thick border around the outside and normal borders between the cells. This is a built in style in Excel. When I try to create a style for this, I drag the cell selection into the style section and it messes up the borders. The borders if the selection change to all Thick borders except for the outer right and bottom borders.

I use this format style all the time and really need to have it work properly as a style.

I figured out what is going on but have no idea how to do what I want to do. When the style is saved, it only uses the upper left corner cell for formatting. So this is useless for what I need.

Does anyone know how to do what I need?