I should clarify I am not an admin and have no access/perms to fix this.

However, running an automatic mail notifier can be difficult and
time-consuming because of bounce/invalid-mail processing and the
possibility of ending up on antispam blacklists.  So *maybe* that's
why this feature does not work.

Also, I notice there is an issue-specific Atom feed for each issue.
Perhaps following these feeds makes life easier?
e.g. https://bugs.ruby-lang.org/issues/8741.atom