Live email notifications on subwiki are sent only after instance restart

Preconditions:

• The Mail Sending should be configured on Main Wiki
• A local user exists on subwiki and has an email address set in its profile
• In webapps\xwiki\WEB-INF\xwiki.properties set notifications.emails.live.graceTime = 1 to enable the sending of e-mails after 1 minute. Make sure the line is not commented out (doesn't have an # at the start of it).

1. Login as Admin
2. Create a subwiki
3. Log in as a simple local user on the subwiki (with email address in the profile)
4. Click on the bell in the top right corner
5. Click on Settings, in the right side of Notifications
6. Set "Email Frequency" to Live
7. Set ON all toggles in the Email column
8. Log in with another user or with Admin
9. Create/update/delete a page
10. Comment in another page
11. Mention the used user in the content of a page

Expected results: An email is sent to the user that has the notifications set to ON, Live.

Actual results: Nothing happens. The XWiki instances needs to be restarted and after that the emails are recived.