@mention doesn't send email to mentioned user

When I get "@ mentioned " in a shared XD prototype that has been shared with me, I do not get an email notifying me of being tagged. I have allowed all emails in the preferences. I can see the notification inside the Cloud desktop app but I don't always have the app open. Why do I not get an email for this? I get an email if I am the one sharing a prototype of any comments or actions happening so why not when I'm specifically tagged? Just because I am not the one sharing?