I got the https://tbc.wowhead.com/item=34204/amulet-of-unfettered-magics today, but as soon as I equip it, it gets replaced by any other neck in my bags. My solution for this (while keeping Itemrack on) was to remove any necks in my bags so it stayed on.
I disabled all other addons and enabled one addon at a time until I found out it was Itemrack that was the culprit.
I haven't seen anyone else report this yet, so I figured I should.
I haven't found anything in the code yet for this particular item, but perhaps someone else has a clue of where to start looking.