Strongbox with "fully linked" mod didn't fully link my 6-socket

I was farming city of sarn in merciless when i encountered a white armourers strongbox. I transmuted it and got the fully linked stat and then I corrupted it. I got 7 items from the box, all corrupted, all of them were fully linked except the 6-socket.

you sure the item didn't drop from the last monster you killed?
aw, i see it's corrupted. looks like a bug and you lost a divine orb.

My guess is that the corruption is rolled after the linking. So you had a crypt armor drop which could have been of any rarity and sockets (even a white 1S), then the vaal corrupted it into what you see there.

Could be wrong though.