Attendee Info not returning from API

Background :

I’m retrieving past Webinar’s from both
(a) participant details - from ‘https://api.zoom.us/v1/metrics/webinardetail’, and then, 
(b) registration details - from ‘https://api.zoom.us/v1/webinar/registration

I’m able to retrieve both details for most of the past Webinars. They match up to Zoom’s Attendee Reports.

 

Issue

However, there is 1 past webinar, that endpoint (b) is returning empty records in node ‘attendees’. - there should be records (as I cross checked in Attendee Report).

May I know what could be the possible root cause ? How can I make those records returned?

 

Note: I’m aware of alternate endpoint (*just guessing) ‘https://api.zoom.us/v1/webinar/attendees/list’, but I need the details in response (b). 

 

Appreciate some guidance. Thanks!

It works for all others, just having an issue with one?

What is the id of the one your having an issue with so we can look.