Status->Email logs should only show failed emails.
You say the test works fine, and it was all working OK two weeks ago, so you have to ask "What has changed?".
Because there are no entries in the email logs, my gut feeling is that your email provider or the recipients email provider may be blocking the messages possibly based on some spam or content filter settings that may have been changed in the last two weeks.
If you can prove your messages are being accepted by your mail relay, then the issue is not with your Fusion installation. If the email connection is not SSL/TLS then a simple packet capture on the relevant port will be enough to prove.