Just a small update that I took a look at “Monday”. It’s a little interesting because it looks like we’re doing all the correct things in setting up the calendar.
Ideally what should happen now is that we use your site’s locale to set the calendar’s locale (not user’s locale). If we use “en-gb” for example, it should use Monday per fullcalendar/locales/en-gb.js at v4.0.0-alpha.3 · fullcalendar/fullcalendar · GitHub, though I am seeing that is not the case despite the docs saying so - weekNumberCalculation - Docs v4 | FullCalendar.
We can force a “Monday” by using an “ISO” setting on the calendar itself but it does not feel right.
In any case stay tuned for an update. We are using a very old version and could use a refresh.