[Plugin: Event Calendar / Scheduler] Unable to save or view events in the Scheduler

I’ve installed the latest version and everything displays ok, however I’m unable to save a new event. The event is displayed but disappears when the page is refreshed. The log says that an incorrect IDs has been passed and there is no INSERT statement. I can enter events via the admin console but these are subsequently not displayed in the schedular but are displayed in the Upcoming Events widget! The scheduler produces a script error trying to access dhtmlxSchedulerConfiguratorLoad.php page to retrieve the XML of events. I’m assuming this may be a permissions problem but am not sure what I should be doing. I would be grateful for any assistance if anyone has come across this already.

https://www.ads-software.com/extend/plugins/event-calendar-scheduler/