The navigation menu on all devices tested works as expected in portrait and in landscape mode, except on one of our iPads. This issue can be observed with an older iPad. With the newer ones, or with the iPad Pros it works fine again in landscape mode. The portrait mode works fine on all devices.
On an older iPad the navigation menu that appears on landscape mode is nothing we designed or expected. It should be a hamburger menu, but it is a static navigation bar, that doesn't work.
All input is much appreciated.