Oh, well apparently media depuper was blocking new media items from being created. I turned that feature off and reproduced the issue. All I did was create a new link with title and web address and copy and paste an image into the image text box. I did not use YOAST duplicate post.
My Active plugins are:
Admin Columns
Akismet Anti-Spam
Classic Editor
Jetpack by WordPress.com
Link Library (obviously)
Media Deduper (installed after the issue started)
Regenerate Thumbnails (also installed after the issue started)
Shortcodes Ultimate
Wordfence (also installed after the issue started)
WPForms Lite
Yoast Duplicate Post
I’m also using the Directory Starter theme if that has any bearing on the matter.