I have for a long time searched for an explanation why I don't get notification when the tasks I am assigned to is updated.
Now I finally found the source of this stupid behaviour. - One must first make a comment on a task to get notifications. This was apparently implemented on purpose in 2018.
This solution is sooo stupid.
If we have a task with five co-workers assigned to it, all five will start by creating a comment "Please notify me". The first co-worker to do this will then receive 5 notifications with "Please notify me". The second will receive 4 notifications and so on.
Of course there should not be sent notification to all users assigned to the whole plan, but there should automatic be sent notifications to the users assigned to the task that was updated - or alternatively there should at least be an option for users to push a button "Follow this task" instead of having to write a comment on the task.
It is surprising how poor systems Microsoft will be known to deliver.