ChrTaylorfrom what I can tell - and it makes no sense to me, every assignee has to comment on a task they are assigned to before they will get notifications of comments made by other assignee's. It's really stupid, but when I create a task and add assignee's, including myself, I then have to comment on the task so I get notified when the other assignee's comment. When they get notified they were assigned to the task, they have to add a comment so they get notified when I add comments in the future. Makes no sense that all assignee's would not be notified when something on the planner task was commented on. So I comment, "created task", and then assignee's comment "Got it" - then we get notifications going forward. There is likely other notification settings you have to review in Planner (I can't remember what I enabled or didn't enable).