Calendar show time in 24h format bug

I am trying to change fullcalendar time format from the 12 hours format to the 24 hours (i put this code in the ****_calendar.js file) when I add this line every event in the calendar stop showing , I checked the js console in the browser but no error was thrown

options: {
    slotDuration: "00:05:00",
	eventTimeFormat: { 
		hour: '2-digit',
		minute: '2-digit',
		meridiem: false

I still can t find out why this is happening I even looked in the calendar.js file in frappe and this option was not even set. Do you know how to solve it or have any lead. I will be grateful thanks !!!