Thanks, it was another of their plugins – Taxonomy order, and in worked perfect!
There was only Clone Posts plugin activated. Nothing changed when deactivated it.
No other plugins are installed yet.
What I noticed now is that it doesn;t show the correct items in a category at all.
It just shows random items…
I could give you the credentials to log in if this will help.
Thanks
Sorry,
I’ve resolved it with content slider.