I've Seen the Other Side of You.
In this episode, the crew temporarily regains their former memories when their neural imprints have been temporarily restored.

When Two revives after this happens, Five meets her in a corridor and isn't recognised at all by "Portia", who demands to know who the "intruder" is.

Built, Not Born.
There is a scene where Suki gets some of her prewipe memories back and one of them is Das talking to Portia about modifying her program to activate unnecessary code.
They're quite friendly and relaxed in this scene, Das even says her first impression of Portia was a terrible one and it only makes Portia smile.
So at some point, Portia and Das were on good terms and actually did know each other.

Which makes it unusual that Portia doesn't recognize Das when her imprint gives her memories back.
I am thinking this is because there were multiple imprints made and the ones that were used were from a time when the Raza crew were at their most ruthless, most likely before Das came on board, given that none of them recognise/remember her.

My theory is that the hostile program installed on the Raza by AU Treffault specifically chose these older imprints to cause the crew to infight amongst themselves and reduce the number of enemies to deal with, as it had no physical presence and limited ship control at this time.