Thanks for the information and link Tom. Response from my hosting company:
“This was one of the first things that I have tried that but didn’t see the query in the Query Monitor on any of the pages of the staging site.
If it’s a background task then it might be a WordPress cronjob but all cronjobs that are currently active on the site are with a minimum recurrence of 1 hour.
I doubt that the query will be displayed because the ‘admin-ajax.php’ is being called with a delay on the front-end due to the loading priority of the files/scripts.”
So if your plugin only makes calls on the dashboard, then can we rule out that its WP Show Posts directly? It seems like we’re leaning towards the possibility that it’s another plugin that’s for whatever reason iterating through the posts in WP Show Posts?