That link isn't there on one of my IDs any more so maybe the OP is the same.  I stopped selling on that ID a few weeks ago and that may have something to do with it but when I sign in now it takes me my summary page, which is actually just my watchlist.  I have to click on Selling/Sold on the dropdown menu up the top right to go to seller hub.  I might try going into my All Selling page and see whether the link shows there.  I don't sell on that ID at the moment but I still have things sitting in unsold.