Scour to 4 link

Maybe I'm dumb, but I couldnt find an answer online and I'm assuming it is a bug.

I was doing the campaign and very happy to finally find my first 5 link body armour.
Bc I dont want any life modifiers I decided to scour it.
But after the scour it has gone down from a 5-link to a 4-socket item.
I lost a socket by scouring.

Never expierenced that before, so I'm assuming it is a bug, unless I am missing something?