Customer is not in the group he should be. Why?
You should start by viewing the customer group change log.
If it is enabled, you can find it in /app/log/et_customergroupautoswitcher.log.
If the log contains the right group, but the customer is in another, then most likely it was changed manually in the admin panel.
It is not the extension's task to monitor such events, but when the status of one of the clients orders will be changed, he will be moved to an appropriate group, unless he is now a in group, that is excluded from the loyalty program.