Emails From Office 365 Workflows Are Sent With Blank Subjects

Issue

When sending emails using the Send An Email action in an Office 365 workflow, the emails have a blank subject line when received by recipients.

Resolution

1. When using an Advanced Lookup within the subject line field, do not copy and paste them from one Send An Email action to another.
2. Re-type the subject line and re-use the Advanced Lookup control to pull in the lookup value.