Ultimate Branding Error: Login Image Failing To Resize Properly

For the past week or so, whenever I go to the login page on one of my sites, I get this error: Warning: getimagesize(/*Site Url*//wp-content/uploads/ultimate-branding/includes/login-image/login-form-image.png): failed to open stream: Connection timed out in /*Site Directory*//wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/login-image.php on line 120 (Note that for security purposes, I've filtered out urls and file directories indicated by /**/). In addition, the login image I've setup via ultimate branding isn't being sized correctly, as shown in the screenshot attached. My issue is similar to this one, however, I can still log into my site and I use a png file, which is allowed by WordPress. I have the latest version provided by the WPMU dashboard. Note that this is a multisite installation.