Enable Showcase controls

I am unable to click and drag items from the “disabled” column to the “enabled” column. This is also the case with the same control used for enabling/disabling the Features Zone, Featured Posts, Carousel, etc.

The control has worked for me in the past, I believe it stopped working with the WordPress 4.1 update. I’ve run into this with two separate WordPress 4.1 installations on different hosting accounts as well, have tried multiple machines in case it was a client-side issue, etc.

Any ideas? Thanks.