Reproduction steps:

1. Add the attached "FullScreenMovieStatusBarTest" package to any project.
2. Build and run the scene for iOS.
3. Make sure, that the internet connection is available.
3. Click "Play(CancelOnInput)" or "Play(Hidden)".
4. Notice, that the status bar is visible(screenshot attached).

Regression introduced in:
5.3

Reproduced with:
5.3.7p3, 5.4.4p2, 5.5.1p1, 5.6.0b6
iPad Mini iOS 9.3.5
iPhone 6 iOS 9.0.2
iPad Air iOS 9.1
iPad Air iOS 8.1.1
iPhone 7+ iOS 10.2

Not reproducible with:
5.2.5f1