Filter options when searching using keywords seems to work more consistently than browsing a category without searching.
To see all items in a category, try searching using the category name, and select the category from the options on the left side of the page, if necessary:
https://www.ebay.co.uk/sch/139973/i.html?_nkw=video+games&LH_TitleDesc=0
From there you should have all the filter options available.