Welcome to the forum. Vaguely recall someone else mentioning this which I think was solved just by powering down the box by unplugging for a minute or so and then trying again. If that doesn't help might be worth having a word with live chat as there aren't many other EE TV users on the forum.
You can get to live chat from the Contact Us page
(expand the Anything Else section at the bottom for the live chat button)