Hi, Michael,
It sounds like you are able to check/uncheck the isRecurring field when creating a new event, but not when you’re modifying an existing event? It looks like this is actually a characteristic of Salesforce events. Salesforce does not allow you change an event to or from “recurring” once it is created. You can change fields such as Recurrence Type and Recurrence Interval, which will create/delete individual events corresponding to the recurrence pattern, but you can not actually change the isRecurring field. Does this address your question?
Emily
