Getting ApplicationName (sqlserver.client_app_name) to show up in an xevent
I have seen this issue before, what seems to happen if you have this type of sequence:


create session
start session
stop session
add columnar data (action or field)
start session


The GUI doesn't show the added columnar data. Your options here would be to directly query the target or to clear/rename the old session definition's XEL files.