How to get SPEEDCHART_KEY on Voucher Line process through CSV upload

I am loading Voucher/Invoice informatoin from CSV file to Voucher Staging tables. The load works fine, the client asked for new requirement to add the SPEEDCHART_KEY which is located on the VCHR_LINE_STG record. I see that it's loading to the table but when the voucher build process runs it omits it from the voucher_line. I believe the voucher_line.SPEEDCHART_KEY has FieldFormula peoplecode behind it...etc

Is there a way to make the SPEEDCHART_KEY remain on the voucher line?