Membership Review - Accounts go Missing

So, I'm not sure what happened as this use to work fine. We have a requirement to have an admin review membership requests.

The way it is working now, an end user will register for an account using the web part. A record will appear in the membership review list (and also in the FBA Users page as inactive). Howevever, now when I approve, the account goes missing from the FBA user list and an approval email never goes out.

Han anyone run into an issue like this? THis use to work fine.. I've already tried reinstalling the fba pack.

Sharepoint 2013 FBA Pack
Has anything else changed in your environment? Usually for SharePoint to be able to send external emails, the smtp server needs to be setup to allow the ip address of the sharepoint server to relay. Perhaps this rule has been removed, or perhaps the ip address of the sharepoint server has changed? That would be my initial guess.

To really get to the bottom of things, attempt to approve an account (which causes this problem) and then go and check your sharepoint log files. I expect there will be an exception in the log file that will give you more detail about what's going wrong. If you search for "fba" you should find any error messages specifically logged by the fba pack. Just search from the bottom up.
Do you need the ability to send emails for account activation? Can FBA work with out email notification?
FBA can work without email notification, but the membership request web part and password recovery web parts included with the FBA Pack both require email.