These 2 articles were referenced on Trackitt.

Article 1
Article 2

Given the discussion about when a porting case can be actioned by USCIS, I thought they might be a useful reference.

Once again, it reiterated the fact that an interfiling / conversion request cannot be actioned unless the PD for the new basis is Current.

Priority Date and Other Considerations

The interfiling request should be based on a priority date that is current, although many such requests are initiated prior to that point. Regardless, no action is taken by the USCIS unless the priority date under the new basis case is current. Additionally, it is required that the adjustment applicant not be subject to any bar on admission based on the new immigrant petition, even if s/he was exempt from these inadmissibility bars at the time of the initial filing.