Ok, I believe I’ve figured out what was going on in my Discourse instance, here are the repo steps:
- Create a group; add some users to that group
- Create a category
- Remove the everyone permission from the new category
- Add your new group created in step #1 so those members can Create / Reply / See
- Make a post in this new category
- Add new members to the permission group created in step #1
- Make sure that these members are set to Watch the category
- Post a reply to the topic created in step #3
The users that you added in step #4 will not get notified of this new post/reply to any topic that was created before they joined the group. They will get notified anytime a new topic is made in the category.
Personally I would consider this is a bug as it is not feasible for me to go back and invite these individuals to all previous topics in this category that they might want to get notified of a reply on (they can view the topic in the web interface), but I suppose it is possible that the system could have been spec’d out to work this way for a reason.