There is one thing that can go wrong here. If your site has an application that redirects, then it’s probably redirecting the wrong way, from https to http. For example, you could have a Wordpress site that thinks it’s http://example.com - you’d need to change that to https://example.com. And then you might not need sympl to do the redirection for you.
Also, it looks like sympl has separated out HSTS from redirection. If I recall correctly, Symbiosis used to enable HSTS with ssl-only. I’d recommend that you should only enable HSTS once you’re confident that ssl-only is working properly, and that certificates are being renewed. Enabling HSTS is a one-way street. It’s a good security option, but if you find something going wrong with ssl, then you can’t revert because all your visitors’ browsers will refuse to use a non-ssl version of the site.