Microsoft Graph API, ErrorInternalServerTransientError when requesting users calendar

Question

Im using the Microsoft Graph Explorer(https://graph.microsoft.io/en-us/graph-explorer) I'm seeing an issue when trying to get a users calendar. According to the documentation, I should be able to see the calendar for a given user https://graph.microsoft.io/en-us/docs/api-reference/v1.0/api/user_list_calendars

my request is

https://graph.microsoft.com/v1.0/users/{user_id}/calendar

where {user_id} is a valid user ID

and receiving the following error:

Status Code: 500

{
    "error": {
        "code": "ErrorInternalServerTransientError",
        "message": "An internal server error occurred. Try again later.",
        "innerError": {
            "request-id": "fcebf782-a028-45aa-9c54-57cbce3e0c29",
            "date": "2017-01-06T16:24:35"
        }
    }
}