Why can you no longer drag an image from your computer?
You can no longer drag an image directly from your computer into the editor. This feature has been disabled because it often caused problems: the image was not displayed properly and the browser sometimes froze, requiring you to refresh the page (for example, using the F5 key).
You can insert an image using the ‘Image’ block or the ‘Text with image’ block. Click ‘Select’ on the left side of your screen and choose the image on your computer.

You can still drag the blocks themselves. In the drag & drop editor, you can drag the ‘Image’ and ‘Text with image’ blocks into your newsletter and move them to a different position.
To find out what else you can do with an inserted image, such as adding a link or alt text, read Adding an image to your newsletter.