It appears that the orientation changed event fires as soon as it senses the start of the change.
This means in the event, using size.width and size.height to determine which what the device is oriented is wrong.
I needed to show some additional information on the screen (it’s help, and it only appears if users select a certain option). I put the code to show it in a method. Then, in the orientation changed event, I used timer.callLater with a 5 msec delay. Works fine in simulator.