@allCag flatten(column) should accelerate, the issue you are facing is different, if you see your reflection status is not complete, can you please click on the history icon to the right of the foot print?
@allCag The profiles show job is completed, when you say reflections are not working when you use FLATTEN, do you mean the query is not accelerated? Can you please send me the profile of the query that did not use the reflection?
@balaji.ramaswamy I have a similar issue. support ticket 117449(internal JIRA DX-51303). I can not create reflection on flatten field. The LOAD MATERIALIZATION job is completed on UI, but in server.log you can find some errors.