Unable to customise slider descriptions

Hi

In the Customise menu > Theme Options > Theme Slider Options, I find that recently I’m unable to update the slider descriptions. When I edit them, the ‘Publish’ button remains greyed out so I cannot save the changes. If I make another change e.g. to the Slider Button link, the ‘Publish’ button becomes clickable but it still does not save changes to the slider descriptions when clicked. Also, I’m unable to see the slider descriptions at all in ‘Visual’ mode, though ‘Text’ mode in the editor does display them. I think this has been happening since the update to 3.6.

Would be grateful for your help