We give our developers the flexibility to set the orientation of the video showing in their app. Despite this flexibility, we highly recommend using the auto-rotate option, so that the video orientation can match how the device is being held. For portrait apps specifically, auto-rotation enables the user to rotate the phone so that the video can occupy the entire screen and potentially lead to higher conversions.
If your videos are not auto-rotating, there are several possible causes, because there are multiple ways to set orientation within an app. The most common reason is that orientation was set at a project level. Even though Vungle's default setting is to autorotate, a master orientation setting like that would cause our ads to show in portrait mode, too.