Post 26B Upgrade, IDR behaviour changed. What has changed?

Summary: We have not changed any IDR related set up post 26B. But what we see is that PO is getting attached to IDR Invoices and additionally were non editable. (Identifying PO field). This has caused huge issue in Invoice processing. We saw that we have PO format profile option set and even that is not stopping the Invoices in populating the PO on invoices.

Has this profile option become obsolete? How can we 'STOP' PO's getting automatically attached to Invoices?

Profile Option Code:AP_INT_CDRM_PO_FORMATS
 Profile Values
 Profile Level = Site
 Profile Value = XYZ123456

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