Hi there,
Thanks for writing in.
Is there a way to disable your hosting’s cache? May changes won’t take effect, the popup is not even popping even after setting it live with manual display. Plus, you should add your image as part content and not a background image. Background image will take the size of the container, and container takes it size from the content. If there is small content or no content, then background will be clip or not visible at all.
Try adding your image as content, example,
<img src="YOUR IMAGE URL" >
And you can add that code to your popup source code. Please check this video
https://www.dropbox.com/s/efbwbup9lwgunj5/bandicam%202017-08-06%2007-22-56-815.mp4?dl=0
Please download the video for better quality.
Thanks!