Thread:HugeClockTowerFan/@comment-26216676-20170705152618/@comment-26273552-20170708101932

If you add to the page in source more (the [  ] button under the Ξ dropdown) that will add the page to the category when you save. Alternatively, finish editing your page and THEN add the category by using the "Add category" button on the category rail at the bottom of the page.