A less intrusive workaround has been proposed by my 2nd tier support team. Instead of adding secondary sorting, you can apply a Query Filter to your View and filter by post status "publish". We are continuing to investigate and I will update you with any additional information I receive.
Can you tell me more about how you have multiple posts with the same publish date and time? Our 2nd tier support team is suggesting this is a very specific issue for your site, and can be effectively resolved with the post status filter workaround. Was this content migrated into your site somehow? I am trying to understand if there's a broader scope to the issue, like a compatibility problem with another plugin, or if this is not a real-world problem that other users may experience.
Hey Christian - Sorry I missed your last message. These records were all imported from CSV - which would explain why they have the same post dates.
I use wp all import and the wordpress importer often to get data into sites, as I'm sure many other developers and site owners do - not so much of an edge case.
Do you have access to the original CSV file that was used to import the content using All Import? Or the WordPress Export file used to import the content via WordPress Import?