What are you using for the m-dot “mobile version”? Is it a WordPress plugin, or is it a different website/platform? Can you share your actual website address so we can check it out and give you more specific advice?
Here is the website: https://invokemoving[.]com/
Please take look here as well: http://i.prntscr.com/Fth7oOFURLehzvJ2UxnX0A.png
I think the above issue is coming from the HTTP mobile version.
Your desktop site at example.com and your mobile site at m.example.com are two totally different websites built on different platforms: the desktop site is a WordPress site, while the mobile site is a Duda site (though you may have gotten your Duda site from a Duda reseller).
There is a JavaScript code in the HEAD of your desktop (WordPress) site which detects visitors coming from mobile devices and redirects them to the Dudua mobile website.
<script src="https://static.mobilewebsiteserver.com/redirect.js" type="text/javascript"></script>
<script type="text/javascript">Mobile_redirect("http://m.invokemoving.com");</script>
As you can see above, the redirection goes to an HTTP site, that’s why you’re getting the insecure warning. If it’s not obvious to you, let me emphasise that this has absolutely nothing to do with your WordPress site.
Fixing this is not a simple matter of changing the mobile redirect URL from HTTP to HTTPS, as it appears the Duda mobile site does not support HTTPS at all: when I tried visiting the secure HTTPS version of the site directly from a mobile device, I got "ERROR_CONNECTION REFUSED" error message, which means the server is not accepting connections at the default HTTPS port 443 (the non-secure HTTP version worked fine).
So that’s something you’ll have to contact Duda (or wherever you for this mdot mobile site from) to fix.
That said, personally, I believe the era of having separate mobile and desktop websites is long gone. These days most websites use the responsive approach, meaning one single website and address that automatically adapts the page layout and design to suit different screen sizes, from tiny mobile screens through desktop computers to giant TV and projector displays.
Good luck!