I have tried to remove the parent / child relationship and display the image in the parent widget but the bug will occur anyways.
Open SafeZoneTestWidgetBP, set screensize to iPhone XS Max and see that safe zone is working correctly
Open ParentWidgetBP in Content/Widget
See the alignment being broken
Reopen SafeZoneTestWidgetBP and see that the alignment is broken.
Simulate in PIE (don't forget to set the iPhone XS Max settings in Editor Settings > Play) or build for iPhone XS Max and see that the widget is either not misaligned but safe zone is ignored, or the widget is misaligned.
It will be displayed as it should from time to time, but will definitely be misaligned on the second try.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-72306 in the post.