Select Recipient on form

I followed this tutorial a while back on how create selectable recipients for a contact form 7 form: https://contactform7.com/selectable-recipient-with-pipes/

It has been working but has recently stopped. I get the “There was an error trying to send your message. Please try again later.”

I have WPSMTP installed and configured on the site, it successfully sends test mail, that has ruled out a SMTP error. Although it show a DMARC warning, however I don’t think this should be preventing the form from sending.

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