Encrypted emails are empty

Hello,

I’ve been setting up S/MIME on my RT instance and I manage to send encrypted emails back and forth, however I have the issue that the emails that are sent from RT are empty. The ticket log shows that an email has been sent with a p7m attachement, which I assume must contain the encrypted body of the message, however when I receive the email in my mail client, it is empty, although correctly marked as S/MIME encrypted. I have the same behavior on both outlook and thunderbird with different email addresses.

The email as sent in RT:

What it actually should contain:

What I receive (screenshot is from another email hence the different case number, ignore this):