Neatline point image not showing

Hi, I'm using Omeka 2.3.1 and Neatline 2.5.1 -I'm trying to add a point image to a neatline record and I can't get it to show up. The file address I'm using is this image comes from the same Omeka instance that the Neatline exhibit is in. I've been able to do this in the past with other similar Omeka images but none work. I've tried random .png files online as well with no luck. Any thoughts?

Sorry, haven't heard from anyone yet and I really need this to work for a course I'm helping with trying to layer transparent images over a map. I've tried using different browsers, several different web accessible png images, tried it with different Neatline exhibits I've created - all with no luck, the point image layer just doesn't show up. Hoping it's something really obvious I've missed!

Have you checked the Neatline Community documentation or tried leaving a github issue?