Updating a OnlineMeeting participants OnlineMeetingRole to Coorganizer sets it to UnknownFutureValue in the OnlineMeeting but not the Teams UI

Describe the bug

I'm trying to change an OnlineMeeting participant's OnlineMeetingRole to OnlineMeetingRole.Coorganizer but the returned OnlineMeeting is showing the participants OnlineMeetingRole as UnknownFutureValue.

However the teams UI is correctly showing the participant as a co-organizer.

Expected behavior

The retrieved OnlineMeeting object should show the participants OnlineMeetingRole as Coorganiser in the MeetingParticipantInfo for each attendee.

How to reproduce

The OnlineMeeting was created via an Event with

var graphEvent = new Event
{
    Subject = $"Testing event with online meeting - {n}",
    Start = new DateTimeTimeZone
    {
        DateTime =  "2025-12-18T14:00:00",
        TimeZone = "UTC"
    },
    End = new DateTimeTimeZone
    {
        DateTime = "2025-12-18T15:00:00",
        TimeZone = "UTC"
    },
    IsOnlineMeeting = true,
    OnlineMeetingProvider = OnlineMeetingProviderType.TeamsForBusiness    
};

I retrieve the OnlineMeeting participants and update one of them to have the OnlineMeetingRole.Coorganizer role. Where onlineMeeting is the retrieved onlineMeeting object, userId is the onlineMeeting organizer

var onlineMeetingAttendees = onlineMeeting.Participants.Attendees;

var updatedAttendees = onlineMeetingAttendees.Select(a =>
    {
        if (a.Upn.Equals(attendeeEmail, StringComparison.OrdinalIgnoreCase))
        {
            return new MeetingParticipantInfo
            {
                Upn = a.Upn,
                Role = OnlineMeetingRole.Coorganizer,
                Identity = a.Identity
            };
        }
        return a;
    }).ToList();

await client.Users[userId].OnlineMeetings[onlineMeeting.Id]
    .PatchAsync(new OnlineMeeting
    {
        Participants = new MeetingParticipants
        {
            Attendees = updatedAttendees
        }
    })
    .ConfigureAwait(false);

Then re-retreiving the online meeting then shows the attendee with UnknownFutureValue instead of Coorganizer.

SDK Version

5.98.0

Latest version known to work for scenario above?

NA

Known Workarounds

NA

Debug output

</details>


### Configuration

OS: Mac

### Other information

This bug was raised and closed for a similar issue with the Java SDK: https://github.com/microsoftgraph/msgraph-sdk-java/issues/1281

Start by reproducing the PATCH and retrieval flow for OnlineMeeting.Participants.Attendees using OnlineMeetingRole.Coorganizer in SDK version 5.98.0. Inspect the handling of MeetingParticipantInfo and enum values, and compare the linked Java SDK issue for context. Done means the retrieved attendee reports Coorganizer rather than UnknownFutureValue, with regression coverage if the relevant test location is found.