I have a custom push transition between view controllers embedded in a
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
I've managed to fix my issue by adding the following line before
toViewController.view.frame = [transitionContext finalFrameForViewController:toViewController];
From Apple's Documentation for finalFrameForViewController:
Returns the ending frame rectangle for the specified view controller’s view.
The rectangle returned by this method represents the size of the corresponding view at the end of the transition. For the view being covered during the presentation, the value returned by this method might be CGRectZero but it might also be a valid frame rectangle.