H10 Windows 11 Tablet - Video display problem

Hi, I’m new to the Forum and I may be putting this in the wrong place. However, my difficulty is with video playback.
If I open (BBC iPlayer, You tube or other streaming video) if I stay in Portrait mode the video seems to slide behind the other items on the screen leaving a black space where the video should be playing. I can move the slider bar at the side of the screen down but this only reveals half the video and when I release the slider it centres the screen display again and the video is hidden. It works fine in Landscape view or full screen mode both portrait and landscape. I have updated Windows 11 to the latest version and have installed the latest Intel UHD Graphics 600 drivers from Intel but the problem is still there. Any help would be appreciated