Same problem here as well. I have been using the plugin for week and all of the sudden this AM the calendar stopped to display and is showing a 404 error. I have deleted the plugin and all calendars, recreated and same issue. Additionally when in the admin page for the plugin the preview calendar button does the same thing, does not show the calendar, just a 404. I can directly embed the iframe code into a blank page and it works just fine, so I know the code is correct. I also tried to disable all plugins and revert to the default theme… no dice.
There has be absolutely no changed to the site in the past few days leading up to this event.
Stout…. help.