The described behavior is expected when the Scheduler's DataSource transport configuration is not configured, as mentioned in this thread
in which the removal of edited events after pressing cancel is discussed. As you can see from Georgi's explanation in his post
, unless the events are synced they are considered temporary and are removed.
So the options are: to configure the dataSource, see for example one
of our demos, or to set unique id's to the created events (see this dojo