PO Project ID not automatic show in Voucher Adjustment entry screen

Why project id from PO screen & Receipt screen not automatic show in Voucher adjustment Entry screen?

My step is:

1) PO screen (create new PO and save with project id)

2) Receipt screen (Select PO created just now)

3) Voucher (Select Receipt PO, but project id not show)

p/s: I already testing in SL standard demo. Checkbox in receipt screen for 'Create voucher for receipt' tick already. But i don't know why project ID still not show.