I'm having a similar problem. Since very recently, when I attach images and place them inline in editor, they appear during the edit, but when I submit the post all I see is a name (eg image1.jpg). Opening the editor again, the image is gone, in both WYSIWYG and Original). If I then reload the images, place them inline, preview them and then submit, they appear in the published post.
This has happened on 2 occasions today. iMac, Safari (latest versions). @Howdy @Chrisw