This was because Grant Purpose was re-named to Special Request on the recommendation form but the email was still looking at the Purpose Key. To resolve, you can re-set the recommendation form back to the default and if you do not want the grant purpose on the form, just delete it and save the form.
It will still show in the email, but will not be a field that donors can type into on the form.
Steps to Duplicate1. Donor logs into DC NXT and submits a suggestion
2. Foundation receives email showing grant purpose field blank