The problem ist that 2fa may cause communication errors between the clients and the server. Request, which are initiated by the clients, may not reach the server. Then, notifications will not appear on the parents device. I personally experienced this issue, when 2fa was activated. On my Mac I was even regularly logged off with 2fa turned on because of communication errors. Also: When I sent a request from my Windows PC, the notifications often did not appear on the parent’s device. So, I’m well aware of these issues.