Do you use Firefox by any chance? After I started using Firefox Quantum, my Wikia tab favicons remained the same, but if I put them in favorites or bookmarks toolbar, the images were wrong or had that default wikia boxed V.
Today, however I finally manged to track down the problem. Firefox takes the favorite icons from "Wiki.png" image.
Example from Tomb Raider wikia:
This is the correct icon that appears in the tab: favicon.ico
This is however how the icon looks in the bookmarks tab: wiki.png
