SSL Explanation Point

If you have anything, external scripts, assets, videos, whatever that is not withing your secure site, or if it is being accessed by using http then the page is breaking the rules for using an ssl certificate and is no longer secure, and browsers will show the 'lock' icon with an explanation mark to indicate this.

Usually that exclamation point alert icon is caused by some of the page being secure while other parts (images or scripts) aren't.

Basically, you're providing an https page but linking to an image or script using http.

This image and any others like it are the likely culprit...

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