I recently was able to use the in game calendar to create an event to my guild. I tested the feature by inviting my own alt to the event then logging over to the character to see if I could accept/rsvp. When I logged over to the invited character the day of the event on the calendar is replaced with a large question mark and every day following that is a large blank space and no longer displays any of the automatic events such as pvp weekends after the date of the event. Other guilds have reported to me that using the event creator in this manner has produced similar results on the calendar of the invitees.
Unsure whether this is a bug or not, but my other characters cannot see the event to sign up either.