I’m actually not sure, if the current behaviour shows a bug:
All users of our community are watching by default a specific category for opening hours. We’re announcing them very shortly, so it’s important they receive them (if they want to).
Unfortunately, creating a new thread won’t push any mail to our members. They miss the opening hours except somebody is answering thread. Than, everybody get the answer to but.
Are they active on the site at the time the topic is created? There is default suppression of email if you are active on the site when the content is created.
Other than that, if you are watching the category, you should get emails when topics are created in that category. Check your Admin, Email logs.
Dunno, should work. Works for me across dozens of Discourse instances. Anything unusual about your setup or configuration? How do you know these users are watching the category?