Satisfaction Survey (CSAT) not sent when plain text format is selected

Summary

When the plain text format is select in the user profile the satisfaction survey won't be sent.

Environment

JIRA Service Desk 3.1.4

Steps to Reproduce

1. Enable the CSAT;
2. Resolve an issue.

Expected Results

The survey should be sent with the "resolved" issue notification.

Actual Results

Only the resolved message is sent. No survey.

Workaround

Change the Email Type to HTML.