We are using the Team Calendars Plugin v 5.3.10 on Confluence 5.10.8.
When I add a new event on my personal calendar, if I leave the "Who" field blank and create the event, when I see the event on my calendar, it is assigned to a random user (not me, and not always the same other user). If I do the same thing and put my own user in the "who" field, after it is created it is now assigned to me and another random user.
I can't find any other question here that addresses this issue -- is this a known issue?