The popular WordPress builder Elementor often has mixed content issues on the homepage. When this happens, visitors won’t get the secure SSL padlock in the address bar when they visit your homepage. But all your other pages are seemingly secure. It’s just the frontpage.
I had problems with one of my domains. I was able to send e-mails but was unable to receive any e-mails. Here is what I did to fix this issue. The domain uses Cpanel and Cloudflare CDN but this also works for domains not running on a CDN.