Comments to my posts often being rejected and not sent to my spam folder

I am using Wordfence and Akismet and I moderate all comments.

But for months I’ve had people complain about not being able to comment because they’re told they are being marked as spam.

They are NOT showing in my spam folder. Sometimes they are able to go back a second time and it works fine.

How can I fix this? Where would the issue be stemming from?

The page I need help with: [log in to see the link]