The WYSIWYG view of unlinked elements show elements one below each other. Images and their captions are displayed in separate zones of WYSIWYG.

WYSIWYG pane with images without captions

When you add a image to an article, but you don't link its caption, the WYSIWYG pane splits in two parts: the top part shows all linked elements, and the bottom part shows an empty caption. If you add more such images to an article, each of unlinked captions is shown in WYSIWYG.

WYSIWYG pane with images hidden

The WYSIWYG view of linked elements with images hidden shows placeholders instead images. To enable such display, on the Options menu, select WYSIWYG options, and then untick Show images, tick Dispose as on page and tick Show area borders.