Add_subscribers_to_board not sending notification

I’m successfully subscribing a guest to a board and adding them to a person column and it’s showing up fine for in on the guests and my end. The only thing is, they didn’t get a notification that they were subscribed to the board, or to the item, or when an update is made on the item they are “subscribed to.” No bell notification or email notification. I feel like it was working last week and I haven’t changed any code and all of the sudden it stopped working. I have checked their notification settings and everything is checked.