Original question - https://success.salesforce.com/answers?id=9063A000000lFXiQAM. I have the same issue with selecting users in the Attendees search bar when creating an event. I log in as a community user (Customer Community Plus) and try to create a new event and invite users from the same community. The main goal is that those users should see this event in their calendars. But I cannot select user records. I only see their corresponding contacts.
This user can see other users in the community. When I search for other users in the Assigned To field, other users are shown.
The admin user can see both the contact and user records.
Does anybody know what's going wrong with the Attendees search bar?