Make sure to check the help article about the Force Refresh setting associated with Auto Refresh linked above. Your NVR may have a strict URL implementation that’s causing the issue when the Force Refresh option is enabled.
I couldn’t get the video to load. From your PM, it looked like the stream wasn’t loading at all even just in the preview window. If that’s the case, make sure to check the Google Chrome - Mixed Content - Media Not Showing thread mentioned above (assuming you’re using the exact URL you are able to load directly in your browser).
But if the media stream does load when you first load the dashboard and only has issues after the autorefresh interval, check the Force Refresh help article linked above.