I’m using beta 15 on a Mac with the json output. When someone joins a call, the ListParticipantsResult shows one value for the user_id. However, for subsequent update events it reports a different user_id. Finally, when the user leaves the call, the original user_id is reported.
I’m thinking this is a bug since there’s no other way to uniquely track participants.
I can provide the json objects if that is helpful.