The primary category has been selected and shows up in the modules mentioned in the link you shared. However, we would also like the option for the “Show primary category first” in the “Single Post Categories” element.

Our use case is that on a post page, we are showing the categories assigned to that post using the “Single Post Categories” element. We would like to have the primary category appearing first in the list, as opposed to “Alphabetical” or “Parent category,” which are the only options in the Settings tool (https://imgur.com/a/ISqZgVJ).

I realize this is not currently available, so I am making a feature request to have “Show primary category first” added as an option to the drop-down for “Tags order” in the “Single Post Category” element.