Basic launch image problem iPhone 6+
I can’t get good launch-image performance on iPhone 6 + , iOS 8.3, using AIR v 17 and publishing with Flash Pro CS5.5
I’ve tested what I understand to be correct launch-image dimensions and names: 1242 x 2208 and ‘Default-414w-736h@3x.png’
I’ve also tested:
‘Default-414w-736h@3x~iphone.png’
‘Default-736h@3x.png’
I create a 1080 x 1920 stage, add the launch image and get:

Letter-boxing is supplied by iPhone! I've drawn test lines on my stage, which has been shortened lengthwise courtesy of iOS 8.3
I've read that people were having problems like this many months ago, but that they've been resolved in the lastest AIR releases. So it must be me. What am I doing wrong?
And, as a follow up question, is it possible to add launch-image info to the application descriptor .xml that will be picked up in the app's info.plist?
