When adding attendees to an event by entering their email addresses into the Invite Attendees field, the web UI fails to add the attendee if you enter an email address and simply click Save to save the event. After some testing it seems you need to press Enter after entering the email address to cause it to be added as an attendee before you click Save. At least two users at our site have found this behavior non-intuitive.

Possible improvements:

• update the web UI to add email addresses as invitees when the user clicks Save, even if they didn't type Enter at the end of the email address.
• update the web UI to provide feedback as the user types email addresses into the Invite Attendees field (e.g. 'No match. Press Enter to add as invitee')
• update the web UI to display a warning under the Invite Attendees field if the user clicks Save when an email address has been typed into the Invite Attendees field but not added as an invitee.