I have a strange problem with a simple Send Email action. The action should send an email to a group of people, these people are in an Exchange Online Security Group. In this action there are people being CC'd & BCC'd. This works fine, until it randomly stops working. Then after a few days it will start working once more. What I dont understand is that the users copied in receive the email, just not the group.
Going in to check on Mail Flow in Exchange shows me the same thing - no email sent to this group. Yet when I check the mailbox of the CC'd user, there is the group in the 'To' line. Sending manually to this group works fine from Outlook, it is only an issue from Nintex.
Workflows on the list were disabled for some work and then re-enabled again without issue. Send Email works but not to the group. The error I get is:
System.Activities.Statements.WorkflowTerminatedException: The message could not be delivered to one or more recipients.