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I agree with what effectdigital said. It looks like everything is in place and your non-www and you http versions of the website are redirecting to the https-www version of the site.

There could be many reasons for this happening.

Did the website go through a recent update? Have you changed the site's content?  Did something change on the robots.txt file? I'd also check if the pages suddenly changed to "noindex" or "nofollow".

I'd recommend you run an audit and check all technical issues first

If the GA tracking code is on the website, then it will capture the traffic regardless of whether GA is setup with the http or https version of the site.

You might also find this MOZ Question and its answers useful:

https://moz.com/community/q/will-changing-the-property-from-http-to-https-in-google-analytics-affect-main-unfiltered-view

Running a quick "site:" search on your website, I can see that there are a handful of pages that are indexed. I can also see that you only have 2 posts up and they were published very recently. Additionally, a few elements on the menu are not linked to any pages. So I'm wondering if the site is relatively new or has been redesigned recently?