Same thing here with wordpress version 5.8. New Reproduction list keeps loading. It seems to be a jquery version error:

Uncaught Error: Bootstrap's JavaScript requires jQuery version 1.9.1 or higher, but lower than version 3
    at bootstrap.3.3.6.min.js:6:216
    at bootstrap.3.3.6.min.js:6:318
Uncaught TypeError: Cannot read properties of null (reading 'scrollTop')
    at constructor.getScrollTop (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:118172)
    at members.constructor.queryScroll (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:156980)
    at members.constructor.displayEvents (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:110785)
    at renderEvents (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:128351)
    at reportEvents (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:128770)
    at eval (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:140571)
    at _fetchEventSource (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:141122)
    at fetchEventSource (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:140129)
    at fetchEvents (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:140049)
    at fetchAndRenderEvents (eval at <anonymous> (fullcalendar.js:1:1), <anonymous>:1:128677)