Can you only add separators to the Scheduler atpage load? I try to add a separator(s) after a callback where I change the StartDate, but the separators do not show. Thank you.
It looks like there is a bug - the updated separators are sent to the client side during a full update (using CallBackUpdateType.Full) but they are not updated on the client side. It will be fixed in the next release.
Thanks for reporting the problem!
It's now fixed in build 5.8.1928 (downloadable from the sandbox).