I guess this must already be answered somewhere, but I cannot find it in the Forums or Documentation.
I set up a site-wide Related Posts list using WPSP, located in the Sidebar when individual posts are viewed. (Even for just a simple word list, WPSP is more useful than the standard Related Posts widget because I can select or exclude posts from the list by categories.)
However, when I select Date as the organising criterion, it seems to deliver them first in alphabetical order of categories, and then by date. So if a category beginning with ‘A’ has an old post, that always appears as the most recent post.
I’m sure this is not what you would intend, so please tell me what I have missed. (I have currently set it with no categories selected, so that all are delivered.)
Our apologies for significant lack of information on the documentation. WP Show Posts is about to get a big overhaul and doing a documentation for the current version now may end up getting a redo after the changes are applied.
As for the problem:
Can you tell us how you’ve set it up? The default order, assuming you didn’t change anything, is actually sorted by the most recent post as shown here: https://share.getcloudapp.com/mXu1G170