Missing Categories in Archive Config

Hi All

First of all apologies if this post is in the wrong forum.

I’m running WordPress 4.4.2 running Weaver Xtreme Child theme and having an issue with displaying the contents of an posts archive.

I want the archive to display one specific category only.

I’ve tried a number of widgets, all seem to have the same/similar issue in that when I try to configure them in the “visibility” part of the widget only my first two originally created categories appear in the drop down

Although if I go to Post -> Categories all four are being displayed as they do on the indivdual post pages.

Can’t see it being the widget/plugin code as they all do the same thing.
As far as I can tell the Categories are all ok as they show up elsewhere on the site ok and function as expected.

I’ve tried rename one of the new cats starting with an “a” but that did not change anything.

One of the missing cats has 3 items in it, the other none.

Any thoughts on where to look or better still how to fix.

Thanks
Geoff
Novice at this WordPress stuff