Hello,
Could you please share the screen shot of MD04 and configuration that you have done?
Once the STO outbound delivery is created then ATP check carried out, with the checking rule you assigned to the combination of the delivery type and supplying plant.
The indicator "ATP Confirmations Relevant for MRP" is set for the combination of the checking rule and delivery type
Read F1 help of field ATPCONFMRP from V_161V The quantities available in the supplying plant and confirmed by the ATP check are considered to be a receipt in the receiving plant on the confirmed date.
In your scope of check OVZ9 active Incl.purchase orders field to have the confirmation date
Also are you using a confirmation control key for for Shipping notification or Inbound delivery?
Did you read KBA 2195518 - Everything about stock transport orders and the ATP check
Best Regards,
R.Brahmankar