I am experiencing a strange issue where sometimes the Send an Email action completes but no email is actually sent. Prior to the email being sent there is a To Do Task action - the email will send if some users complete this task, but when other users complete the preceding task it does not send.
Example 1:
User A starts the workflow
User A completes the To Do Task
Email is successfully sent
Example 2:
User A starts the workflow
User B completes the To Do Task
Email is NOT SENT, although the action and workflow are completed without error.
This is happening in a large workflow.
I have created a second test workflow that just has the To Do Task followed by Send an Email and the behaviour is exactly the same.
Given that the workflow is running under User A in both cases, how can the difference in the email behaviour be explained.
This relates to NW2013 on-prem.