Editor buttons not appearing

I’m using U Extended Comment for two purposes: to provide a list of recent comments in a sidebar widget, and to provide a visual editor for comments. I’m now on WordPress 3.4.2 with the multisite option, using a child theme of Brunelleschi.

Since the upgrade to 3.3, the recent comments widget has continued to work, but the editor buttons are missing in the comment editor: I just get the tabs with ‘Visual’ and ‘HTML’; ‘Visual’ has but one option, ‘Paragraph’.

I see that other people have also raised this problem. I’m not using any minify plugins, and in fact the problem still exists when all my other plugins are turned off. Other posts about the same issue have no replies.

Is there anything I can do to make the rich editor buttons appear properly?

https://www.ads-software.com/extend/plugins/u-extended-comment/