According to this article, you are able to enable the SSL certificate in your Shopify dashboard. Make sure you've followed all the step.
Or you can learn more about how to fix the “SSL unavailable” issue if SSL unavailable appears on your Shopify admin dashboard
Hope it helps!
Cal here from Shopify, thanks for reaching out to us. I'd be happy to look into this with you. Is it a Shopify bought domain, or a third party domain?
Can you share the domain URL and I'll have a look at this from our end? Thanks!
Hi again! It looks like there are some AAAA records on that third party domain. Please remove any unnecessary records, and focus on having the correct A and CNAME record for the domain:
Let me know how this goes!