Unfortunately, I am not finding the issue and it is not replicating in any other site I tested nor with the WordPress codex themes.
Not sure what is unique about your site, but if you say it still does it with a codex theme and with only events plugins active it could something on your server, but if that is the case there is no way for us to test that.
Until there is some more information on the issue there is nothing I can do on it right now.