Strange output in screen options area in the admin

I'm getting some strange output on the admin pages for list questions and list answers. In the screen options slide down, there is some garbage output appearing (it gets worse when I activated the Admin Columns plugin).

See the screenshot to see what I'm talking about. In only happens on these two Q&A-related pages. It doesn't occur on the posts or pages listings.

Support access has been granted, the site is located at: