Redmine

Hi, I have long term trouble with a watcher not receiving any email. Having a vanilla Redmine v3.3.1, email notification works fine in general. But not for any watcher.
I have a private project (see "private project.png" snapshot). I have also notifications set properly (see "notification setting.png" snapshot). I have a role for a watcher with a read permissions to issues (see "watcher permission1,2,3.png" snapshot). And I have one TEST project's member called "Watcher" with the ""WatcherRole" assigned (see "watcher member.png" snapshot).
Having all this done, if some user "A" creates a task for user "B" and and adds the Watcher member as a watcher, the Watcher receives no email, no matter what changes are made to the issue. No email at all.
I am aware of the fact, the the "WatcherRole" has the read only access only to issues "Created by or assigned to" and tha the Watcher is no assignet to that issue. I do not want the Watcher to access the issue. I just want to notify him by email. (Even if it would be nice, if tha watcher may watch the issue, what is also given by his limited permissions.)
So, please, tell me, what do I do wrong?
Thanks million times!
Milan