TV Go - cannot change any dropdown options e.g. on subtitles

On an iPad with iOS 26.2 when viewing a Saved i.e. recorded programme, I try to add Subtitles the following happens.

I touch the top of the screen and I get a line of icons (see image below) for change the audio volume,  Connect to a box, Subtitles and Screen size.

When I touch any of these icons the screen displays for about half a second and these then disappear not allowing me to access the dropdown list of options. I can do this OK on my iPhone.

Any idea why? TIA