Emails come through, but the field codes do not have user data

This may be a similar problem to the one here: https://www.ads-software.com/support/topic/e-mail-arrive-but-all-user-fields-are-code/

I’m using the Twenty Seventeen theme.

This worked fine before the WordPress update recently. I’ve tried:

1. Deleting the plugin folder and reinstalling the plugin
2. Changing the theme to Twenty Sixteen and disabling all other plugins.

These changes haven’t worked so I’ve put the form back as it was. I’ll need to disable the page ASAP if I can’t find a fix.

Thanks.

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