Mailto link in event no longer working when users are added

[Amber van Overschot]

I am trying to add a mailto link to events for users to register for said events. The link shows as a clickable link in the event unless a user is added in the who field, then the link will show as the html.

Is there any way to make it work with users in the the who field?

We need to add required attendees so they get an email notification.