ATP issue while releasing a PO

Hi Gurus, hope you are fine.

Please, could you help me with this?

At the moment when a PO is being released the ATP performed and informs me that there are missing parts. OK.

I created a new checking rule that allows to check the subcontractro stock, but for some reason the ATP in the missing parts is not taking into account that stock; let me show you:

MD04 for the ROH material:

Now, the ATP during the production order release:

CO09:

Maybe I'm missing something, but why if I have not checked the w/o subcontractor flag in OPJJ, the ATP during the production order differs from the CO09?

Thanks in advance!

Regards.