I’ve been deceived by the fact that when we create a layout with the api, it’s automatically in draft mode and the response say that the parentId is null, so I assumed that the ID was the one of the draft layout, but it was the parent Id, so i had to make a get request /layout?parentId=53 to get the real draft layout’s id.
It seems to be a bug, it not makes things very convenient, but at least there is a way to get the right id.