How do you view the chart? Is it embedded into your application? How? In an IFrame or via some other mechanism?
Yes It's embedded into application. We don't use iframe we use java script.
OK - That's your problem. We never show comments when you embed into "your" application because the Comments feature is part of the Tableau Server Portal - in other words the viz that you embed has no idea that there is a Comments area that people can type in - OUR portal shows this UI.
So trusted tickets isn't the issue here at all. You'd see the same behavior if you allowed the user to login to Tableau inside the frame in which the report will be shown.
The only way to see "Comments" is to allow users to view the viz from inside our Tableau Server pages.