I just reinstalled a fresh copy today, and from the front end running in https and can navigate just fine. But I've noticed that when I am in the administration section and try to return to the main page by clicking the title at the top, it redirects back to http causing the user to appear signed out and icons to not render among other things.
Hovering over the link i can see that its supposed to be going to https, but theres some sort of redirect happening in between forcing it out of https. I can manually put the s back in and it works just fine, and clicking the same link from the non-admin side works as expected.
I tried forcing https via, .htaccess using the default one in flarum/public by adding
# Force https
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
just below the "RewriteEngine on" line, but then I get a redirect loop error. I have a site running on the same domain and it was already configured to force https too. Plus it works fine for most of the site, its just returning from the admin side thats causing issues.