When using the image buttons to bring up the associated menu on the right of the editor, the "Unpublish", "Delete from Draft Site", "Save" and "Save and Publish" buttons vanish.

Steps to recreate problem:

Click on a page in "site content & structure" or create a new page.
Click within the "content area".
Click the Image icon to bring up the "Image" area on the right.
Click on the "folder" drop down menu so show the folders list.

The buttons underneath the "content" area now disappear.

I'm using Silverstripe 2.3.1. It doesn't seem to affect any previous versions.
It is present using Safari, Firefox and IE.

Any suggestions?