Alagad captcha suddenly not working

We've been using the Alagad Captcha on our site for over a year now and everything has been working just fine. But within the last week the image that shows the random code to enter stopped showing up. I've checked all the files and nothing has changed. Had anyone else had this problem before? I have no idea how to even troubleshoot it since nothing has been changed. I have no idea what would cause the image to just stop showing on our form.