Since upgrading to Win10 Ver. 20H2 yesterday, Windows Live Mail now gives me a bogus message after bulk-deleting items in both the 'Deleted items' and 'Junk mail' folders.

All items delete just fine; they disappear from the on-screen folders as shown here, and a check of the actual location where WLM stores messages confirms that the folders are indeed empty.

I do realize that WLM is a 'legacy' program, and have been told that Microsoft wants to see it purged from our systems.  But some of us 'legacy' users do like it and will persist.  It did take some doing and info from third-party forums to even make it run under this latest version of Windows.  Sure enough, this bogus message business is a minor problem, and dismissing the message is simply a mouse-click.  But if this could be rectified somehow, it would be worth it... to me at any rate.