Good to know that you probably fix the issue (based on the edit) !
Just to be sure a future Jira user find this page with this kind of problem, there's a page named notification helper that can help to understand what's wrong : Jira admin helper
Addditionnally in this kind on case you should verify if the mail of the user is correct !
Have fun with Jira!
Hello Atlassian Community! We’re thrilled to announce some exciting changes to incident management in Jira Service Management Cloud, in order to give your teams extra muscle during incidents, and ...
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