I hosted a Girl's Night during Week 3 and invited five people like required, but when the event occured, Jasper didn't tell me at all about Gisette even though I invited her. The game acted as if I had only sent four invitations.
I was also very surprised that Penelope didn't come even though my friendship bar is almost maxed out and I went to her date during Week 2 and she sent me a gift. I've got a tiny bit of rivalry with her ever since the Self-Introductions and her respect bar isn't very high so that might be it, but as the event seems a bit buged, I'd rather mention it just in case