==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): v0.9.7
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version: CentOS release 6.9
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): Mysql
- Web server (Apache or Nginx):Nginx
- Manage mail accounts with iRedAdmin-Pro? yes  v2.8.0
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
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通过web管理页面，通过编辑账号的profile把a账号加入到邮件群组b，加入后在群组b的成员列表里能查到a账号，但是在a账号的profile--Member of Mail Aliases 里不显示属于b群组，给b群组发邮件，a账号也收取不到。
在数据库 forwardings表里也能查到对应的信息
请问这是什么问题，应该如何排查。