Calendar Links not working or showing
SMTP: If your calendar links are not working inside of email and you are using your own custom SMTP like Sendgrid you will need to turn link tracking off or setup an SSL with SendGrid so that you links are secure: https://app.sendgrid.com/settings/tracking
Join Session in Progress - if a user registers for a Join Session in Progress the Calendar link will not display as there would be nothing for them to add to their calendar.