Yes, that would explain it.
You could try - supportedInterfaceOrientations
https://developer.apple.com/library/ios/qa/qa1688/_index.html
Beginning with iOS 6, only the topmost view controller (alongside the
UIApplication
object) participates in deciding whether to rotate in response to a change of the device's orientation. More often than not, the view controller displaying your content is a child of
UINavigationController
,
UITabBarController
, or a custom container view controller. You may find yourself needing to subclass a container view controller in order to modify the values returned by its
supportedInterfaceOrientations
and
shouldAutorotate
methods.