Online calendars like Google and Outlook commonly refresh every 24 hours (but sometimes happen sooner) so recent changes inside of a FlipperForce project may not be reflected immediately. If you want to double-check dates, you can easily open up an event in your calendar and click the link to the FlipperForce activity to see live details.

Other applications, like Apple Calendar, may give you the option to choose how often you want to refresh the calendar.