Purchasing not applying Tax automatically to Standard PO

Hi All,

Release 12.1.3 Module: Purchasing

I've configured a new Operating Unit and rolled out the PO module.

Problem is that tax is not being calculated automatically on PO creation. However, in manage Tax it provides the option to add Tax Code and apply.

I've checked the Tax regime, Tax Codes, Tax default options (Supplier Site), Enabled the Allow Tax in Configuration Owner Tax Options for purchasing.

Worth mentioning that the instance already had an OU and the Tax calculations are working fine (actually the Tax regime and Tax code, Item and Supplier are shared between these 2 OUs).

Can anyone please help me with a setup checklist? What setup am I missing here?