Coursepress Pro using most recent img upload instead of "list image"

We're running a multisite with CoursePress Pro and Membership 2 Pro. Theme is Customizer.

On the page where you view the course units, the img is defaulting to the last img uploaded instead of the "list image" set in the course settings. I can change it back, but as soon as I upload a new image to the media library - for anything, posts, whatever - the course units image changes to my most recent upload.

Any ideas how to fix this?

Thanks,
Kate