-FrA-

I’ve just deactivated all the plugins but yours. Even the WPDM extensions are disabled.

Swapped to twenty-fifteen theme as well, regenerated permalinks, what I get is in the attached picture.

Update:
After last update of the plugin categories in page work again. However, if I try to visualize a full category archive following the “view” link in the category management page, it keeps not to display anything.