Thanks for your reply, appreciate it.

Yes, I'm trying to "auto-number" number, left to right, the columns in the order in which they appear. The columns (Sales Orders) are ordered by the Row sort (Bin Location). I'm not sure this can have anything to do with changing the matrix sort must follow the rows.

Does this explain more? Will row_number over still work to dynamically number however many columns appear (generally 1 to 8 columns).