Appointment isonline property error 'Set action is invalid for property.'

Question

Hi,

Similar question are asked around web but i couldn't find a definitive answer.

When an EWS appointment is created code behind this properties work just fine :

For example for Appointment app = new Appointment()

app.Subject = "Test" // It works fine no errors.
app.Body = "Content" // Again no errors.
app.Start = DateTime.Now // No error.
app.End = end time // No error.
app.location = "Meeting Room" // This is fine too
app.RequiredAttendees.Add("blah@Stuff .com") // No Problem

app.Save(); // Just like this, you can create an appointment with no problems .

But whenever i want to make this an online meeting, i add

app.IsOnlineMeeting = true // According to documentation this property has get and set . So i should be able to set a bool value. But as soon as i add this property change to my appointment ,
app.Save() returns an error. 'Set action is invalid for property.' . According to many people this error comes because IsOnlineMeeting is read only. But how can i set it ? I tried to go outlook and went to account options to set everymeeting to onlinemeeting as default. When i create a meeting from outlook, now every meeting is created with a teams meeting. I thought as long as account is set to send onlinemeetings as default, IsOnlineMeeting property should set itself to true or similar effect should happen. But i had no luck. I can't make an online meeting from codebehind. Should i use a newer tech like graphql ?