DNS Check Successful, can't enforce HTTPS in Github Pages

Question

I'm deploying a website through Github pages. I've done this before but not enough to consider myself professional.

When I go to Github pages in my repository, I add the web address of my custom domain, and for a few seconds it performs a DNS check. When it says successful, I try to click the checkbox but the box is still grayed out.

When I refresh the page it goes back to doing a DNS check and then after a couple of seconds it says DNS check was successful.

I've checked with my DNS registrar and I've created an "A" record with the IP addresses for my site on Github pages and a CNAME record as well.

I tried removing the custom domain and adding it again and that's when it started to go through the DNS check and then success cycle every time I loaded the page, but it still won't unblock the Enforce HTTPS box.