Cron: the silent stop
When WordPress cron or Action Scheduler stalls, scheduled posts stay unpublished and order e-mails and renewals quietly stop — while the site looks fine. Detective records the stall and, in Testing tools, can run the due jobs one by one under supervision to report which one crashes and why.
Mail: the invisible failure
WordPress does not tell you when e-mail fails to send. Mail Detective records the mail server’s actual reason — a blocked PHP mail function (install SMTP), expired SMTP credentials, or a From address rejected by DMARC — and which plugin tried to send. Order confirmations and password resets that “just stopped arriving” finally have an explanation.