All submissions marked spam, not submitted

This is a strange one. We use this setup on multiple sites without issue, but this site is just giving us problems.

The problem is CF7 seems to be labeling all submissions as spam and not letting them get sent in. We’re not seeing any requests for emails to be sent, so CF7 is stopping the submission before it gets to email.

I get the dark orange border and message and the message “Failed to send your message. Please try later or contact the administrator by another method.” In settings, this is “Submission was referred to as spam”

We’ve tried disabling all other plugins and reactivating. We’ve tried two or three Recaptcha plugins, and disabled all. That doesn’t work. Currently using Really Simple Captcha, designed specifically for CF7.

We have verified email is working fine. The problem exists no matter what to email address we set. Outgoing emails from the site are working fine and are not labeled as spam. It’s a CF7 issue.

It’s difficult to ascertain from server logs what’s going on because we’re not seeing any errors.

Furthermore, we’ve rolled back the site to a version that worked fine with CF7 a few weeks ago when form submissions were coming in without problem. If we test that now, it doesn’t work for the same problem – submission is being treated as spam. I even jumped back into an old staging server where the staging version of this site is installed that’s older than the roll back we did. Didn’t update anything. Last time we tried a submission on the staging server, it worked great. Now, with the same configuration, on a different server it doesn’t work.

I also used that staging server to disable plugins to attempt to isolate a conflict. Even with almost all plugins disabled, still the same issue. I’ve not been able to get this site to submit a form in any imaginable configuration.

A few of us have been working on this issue for a couple of days.

What are we missing?

Any ideas? Many thanks!

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