As SFM says, it comes down to signage, and the small print on the PCN.
We have seen things like this in Dagenham before, who seem to be a totally dozy council, but unfortunately, the more dozy they are, the more money they make !
Just looking around in GSV, it seems clear that off-carriageway parking is tolerated in the side streets off Gay, rather than permitted, because there seem to be no signs at all that allow it. Where you parked there are also no signs, but a sign here : -
https://maps.app.goo.gl/PHSiQifGpozdEyWg6telling you that beyond the sign is a Controlled Parking Zone. The times on this sign control the single-yellow lines in the zone. However, your PCN is not for contravening this, but for parking off-carriageway. This has been an offence in London since the 70s and needs no signs or lines. So on the face of it, the PCN seems to be correctly served. Except, of course, that one can see that streets leading off where your PCN was served, allow off-carriageway parking, yet there are not signs to permit it, against the London-wide ban.
So here: -
https://maps.app.goo.gl/zu2zmLznLqV3eMhe8and here
https://maps.app.goo.gl/ew8npkCuBsJNfHJu9and here
https://maps.app.goo.gl/2HKz3Wcwy9b1Sh4Z9and also in part of Foxlands Crescent that is not in the CPZ.
Dagenham Council really have some explaining to do.
If it were me, I'd submit reps on the basis that further up Foxlands Crescent it is clear that off-carriageway parking is permitted by the council and in all the side streets as well. If they come back and say you parked in a CPZ then they condemn themselves, because a CPZ has nothing to do with it.