I think I know the reason, and a solution as well. So the SSL notification pops-up whevever a search is made. This is because the images might be parsed from the content, and served as-is, with the original non-SSL url.
The resolution is very simple, and since you added FTP acces, I placed the following code to the bottom of the functions.php file in the child theme directory (Avada-Child-Theme), I hope you don't mind:
This code basically replaces any occurences of http content with https. It will also endure any updates in the future.
I had plans to include this snippet somewhere in the core plugin code, but unfortunately my tests revealed, that in some cases wordpress still reports that the site URL is non-SSL or vice versa, so this would potentially break installations not affected by this issue.
It should return the images with the proper SSL protocol url now.Best,
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