WordFence – Create a campaign
For WordFence users, it is possible than this security plugin sometimes block the campaign creation because DeliPress handles HTML generated by MJML.
It’s called a “false positive”
In order to fix the issue, go to WordFence > Live Traffic.
You’ll find, in red, an URL like this : wp-admin/admin-ajax.php? page=delipress-….
All you have to do is to click on Whitelist param from Firewall. and you’re good !