I have tested again now and working correctly.
Please check following
1. Your website can run cron. There are many plugins out there to check.
2. Go to Dashboard > Front End PM PRO > Emails and check all the fields are filled. Eg. Announcement subject, Announcement content.
3. refresh your website couple of times after time ends. Eg. you set 1 minute. Then after 1 minute refresh your website
4. Reduce “Emails send per interval” to 10
5. If you use any customized email template, make sure no errors are there. Also check your server log if any error there.
6. You can also check https://codex.wordpress.org/Editing_wp-config.php#Alternative_Cron
Let me know.