splitViewController:willHideViewController not called

[ata01]

I have a split view controller and when in portrait mode the master is hidden. When that happens I want to add a bar button item to the detail vc that will allow to see the master via popover. My detail vc is a split vc delegate and implements the shouldHide, willHide and willShow methods. When running on landscape mode and rotating to portrait this works fine, but when the app starts on portrait the shouldHide is called (and returns YES) but the willHide is not called resulting in not having the bar button. Any idea why is that and how can I solve it?

[Wolfheart]

Now I am standing against the same problem under iOS 5. But with earlier iOS that failure cannot be reproduced. Does somebody have experienced it? I think it's very common case but cannot find nowhere information about tath.