Sending OTP via Email

Setting up OTP via email & SMS but I am having issue with the email being sent out. There is no text in the body of the email.

In the Message field of the Email Agent (using VPE), this is my message:

One Time Passcode: %{session.otp.assigned.val} Expires after use or in %{session.otp.assigned.ttl} seconds

When I receive the email there is NO text in the body, only the subject is displayed. From my testing if I was to call %{session.otp.assigned.val} in the subject line this works!

Example of email being received.

From: bigip@email.com
Sent: Tuesday, 19 April 2016 10:55 PM
To: testuser@hotmail.com
Subject: One Time Passcode
Message: (No Message Text)