It turns out that it is a theme conflict with the Eduma theme.
Uncaught TypeError: moment.tz is not a function
at HTMLDivElement.<anonymous> (default-calendar.min.js?ver=3.1.10:6)
at Function.each (jquery.js?ver=1.12.4:2)
at a.fn.init.each (jquery.js?ver=1.12.4:2)
at HTMLDocument.<anonymous> (default-calendar.min.js?ver=3.1.10:6)
at i (jquery.js?ver=1.12.4:2)
at Object.fireWith [as resolveWith] (jquery.js?ver=1.12.4:2)
at Function.ready (jquery.js?ver=1.12.4:2)
at HTMLDocument.K (jquery.js?ver=1.12.4:2)
Does anyone have a fix? Thanks!