I've deactivated all of my plugins except this one. No updates to themes, no changes to the site.
On a gallery created on November 4th, it seems to work great: http://chicagophoenix.com/galleries/barack-obama-election-night-2012/
A gallery created today it doesn't work at all, same post type, no plugins activated except this one. If there is text is the caption area of the first photo, it will show the thumbnail of that photo (out of 15 in the gallery) with the caption. Clicking that photo opens the gallery, but only three of the 15 photos show in the gallery. http://chicagophoenix.com/galleries/sample-gallery/
If there is no caption on the first photo in the gallery, a tiny black line shows up, nothing else. If you click the black line, it opens a photo, but just opens it as an image, not in the gallery view: http://chicagophoenix.com/galleries/santa-speedo-run-2012/