Fellow collector and friend of HaloFanForLife Kevid Hurd found series 4 (all except Cortana which was cherry-picked out of the box).
The codes for these are as follows:
Artic UNSC Pilot a15111mm
Green UNSC Marine a16111mm
Yellow UNSC ODST a17111mm
Blue Covenant Elite a18111mm
Cooper Covenant Brute a21111mm
Crimson Elite Pilot a22111mm
Purple UNSC EVA Spartan a23111mm
Cortana ?????????
He presents the following video: