Watcher is not being notified
Problem
A specific user who is a watcher of a given issue, is active etc, is not notified through JEMHC. This seems to be a bug https://jira.atlassian.com/browse/JRACLOUD-71205 that causes the user account ID to be missing and the user email to be replaced with a ?, so JEMHC has no way to find it. We log a note in the Report about the problem, but that's it.
We don't have a workaround or solution at this time. Reach out to Atlassian Support referring to the issue above if this impacts you.