I have located an issue with the scheduler in Firefox
It currently is not possible to edit an appointment in Firefox when visiting the following demo page:
https://demos.telerik.com/blazor-ui/scheduler/appointment-editing
Edge and Chrome work as expected.
I noticed this issue in my local project and referred to the demo's to see if I was doing something stupid :-).
I am assuming that the demo's are running in .net 5 and that the demo's are blazor server applications.