When adding an image link using the TinyMCE Editor in eg a Page this link can't be updated. Instead the update removes the image and replaces it with a text link.

1. Insert an image
2. Select the image and add a link with the link icon or Insert > Link menu and click "Update link" (the button text should be Create link...)
   
   
3. Select the image to modify the link or select the option Open in new window by clicking the link icon or Insert > Link menu
   
4. Click Update link
5. Now the image disappears and is replaced by a text link instead.
   

I've tried this in the TinyMCE editor on https://www.tiny.cloud/ and it works as expected, i e the image link can be updated and the image is kept.