Membership 2 Pro and Hummingbird issue

I'm using Hummingbird Caching. I've updated some images on certain pages. But on test computers other than my own, these images are not refreshing in their browsers. I've tried clearing cache and browser data on that test computer but the old images are still showing. I also tried shortening the expiry time on images to 1 hour (not recommended) to see if that would cause a refresh on the content delivery network.

I also made a plugin conflict test and when I disable Membership 2 Pro problem is gone.