I am really sorry, I did not receive your email (still now).
This is very strange and i can not think how it can be possible that only one role work and more than one role not working as it saves as array and array elements can be any number.
Please let me know your WordPress version. Also please send me screenshot of Dashboard > Front End PM PRO > Settings > Emails page.
Also please Note: Announcement emails send by wp cron, so if cron can not run (eg. no visitor in your website ), no emails will be sent.