When I sort by a custom column, I get an empty list
1) I've bought the sortable columns option.
2) I've enabled hidden fields using:
3) I've added a custom field column based on a custom field that stores post IDs
- the field name begins with an underscore, and set the column to show as Post Title
This works as expected when looking at the CPT list, I see the new column, and the correct linked post titles appear.
Now, if I click the title of the column, to sort by the post titles in this custom column, I get an empty list (no posts are shown at all.)