https://www.ebay.com/itm/30445003074...p2047675.l2557
Interesting sale. I tried several times, on a few forums, I believe, to point out this variation but most replies seemed to think that it is was just me unable to catch the boxed sign but I have definitely pulled my copy out more than once and thoroughly examined it under different light sources and concluded it is a fully flush blackout over the area.
Sadly, rare or not, it will likely never catch on as a "must have" among the varieties but this certainly has to be among the tougher transitional versions being so close to the final one and with so few samples having turned up (unless I missed some, which is highly likely).