Other emails send perfectly? Message email send perfectly?
Also note that announcement email remain in queue, By default It will send 100 emails in every hour. https://www.shamimsplugins.com/docs/front-end-pm-pro/getting-started-2/announcement-email-queue/
You can change that, set interval to 5 minutes, wait 5 minutes after sending announcement, then access your website (cron does not work if no visitor in website). Then see is email sending.
Let me know.