I am trying to change my BOM table in my drawing from my item numbers are starting at 1 at the top of my BOM and need to start at the bottom of my BOM. Using sort region I have the ability to sort other columns in forward or backward order, however it won't work for my item number column using my rpt.index.
You can set the direction in table properties.
To explain Martin's answer - rpt.index is the number assigned to each row of the table and cannot be backwards in the table. Instead, the direction that rows are added need to be changed via the table direction setting. This may affect the position of non-repeat region rows - it seems reasonable that a table can't grow in the up direction if it is anchored at the top to a non-repeat row, but it might work.
In other words, if you want the numbers to be top-down or bottom-up the table direction needs to be set to that direction.