I have a number of S120 and S340, S350, and 3C cameras. (Android App)
The S340, S350, and 3C feeds work as desired. While the phone is in portrait/vertical mode the feed starts as a box in the middle, and if you expand the zoom with your fingers it will utilize/fill the entire phone screen to show the video feed. Also the the setting for sound (speaker icon while viewing feed, on or mute) is remembered for next time - good.
With the recent versions of the app since the major redesign, when viewing the camera feed/recording for the S120 cameras (while the phone is in portrait/vertical mode), the feed starts out using the top portion of the screen (instead of the middle), and as you zoom in, the video will only continue using that top portion of the screen instead of expanding to utilize the rest of the screen. This did work properly in the past, so it can/has be done. The sound setting (speaker icon while viewing feed) for the S120 always resets to on/doesn’t remember last setting. This never worked in the past, but would be nice if it did like the other cameras.
(I also am having the same general problems as others with the Group Control buttons taking many presses in just the right way, to even register, and the newest issue of defaulting to All Devices etc.)