Thanks to flowergirlphysicist and others for helping confirm that the missing reply sharing tab on the comment drop down menu is an artifact of browser page size. If yours is missing increase the size of your page (or decrease if that doesn't work) and it magically appears.

EDIT: This fix may not be as reliable as initially thought. NuKinja hates you and it will constantly work toward your suffering for no apparent reason other than blind malice.