missing visual editor for gallery

In brief, I cannot edit a gallery once it has been inserted into a post or page.

I think I should see a placeholder for the images which once clicked, takes you to the image/gallery editor.

All I see is the shortcode so to make any substantial changes, I have to delete the whole gallery and start again.

Please see screenshot to the problem area: https://stephaniewoolley.co.uk/?page_id=130

I am hosting Sketch theme on evohosting, and I realise that is a wordpress .org version, but the forum over there couldn’t help and suggested I try here.

I am using Chrome and have deleted all history, cache etc.

I have added SCRIPT_DEBUG TO WP-CONFIG.PHP file and this has made no difference.

I have tried firefox, safari and chrome and the problem is the same across all browsers.

Can anyone help please?