"WordPress deleted …" but user does not exist?

In the activity log

What “activity log”?

Sorry, “Activity Monitor” on the dashboard.

It may be that someone/thing has gained server level impersonation of your WordPress hosting account – check if site is hacked at Securi.

What “Activity Monitor”? There’s no such functionality in WordPress core.

Could you describe what Activity Log you are referring to?

Ok, it appears that someone has installed the “ThreeWP Activity Monitor” plugin, and that’s where the Activity Monitor is coming from. I can deactivate/delete it. Is there some better way (i.e. core function) that will let me monitor activity?

Other than installing third-party plugins I don’t think there is any Core activity monitor, with the exception of the Dashboard “Right Now” panel.

And I’d guess that the plugin is picking up activity on the server and that it is WordPress itself that you are seeing as a “user”.

Sounds like a plugin that should be yanked to me.

Ok, I yanked it. Thanks for such a fast set of responses from everyone!

Now, any pointers as to how I can learn more about why WordPress itself would be deleting my posts? I have so much to learn …

Are you actually missing any posts? Have you limited the number of post revisions that are being stored in your database?

A site link would help – did you scan at Securi?

I have not yet limited the number of revisions (at least not that I know of – I did not add the code that would do that to the config file yet). The site is at https://www.woodstockdayschool.org And Sucuri says the site is clean.

Are you actually missing any posts?

Yes, the posts that are listed as “WordPress deleted …” are missing.