Shopify will provide you with a free SSL certificate so long as your domain is set up correctly. A CSR would not be required. Assuming that you are using a third-party domain, you'll need to check the DNS records to ensure that you do not have any additional "A" records or "AAAA" records. If you can supply your domain then I can check this for you via public records.
If the domain is set up correctly and does not have any additional records, then we may need to reprovision the certificates for the domain. To do so will require reaching out to our Support so they can help resolve this.
While we’re not able to provide account-specific support via the Shopify Community at this time, we’d be happy to continue assisting you through live chat, email, or callback. Please visit https://bit.ly/3cJkx8V and log in to your account to create a support request.
Since this is the next step I've marked this reply as the solution for the benefit of others who may discover this topic. Thanks!