So I have a strange one.
With every new page/post created, the space between the page title and the muffin builder increased until finally all that there is white space, the muffin builder no longer appears and cannot be accessed (the scroll bar is not there). This is the case for 'pages' whilst for 'posts' the space has increased but I can still access muffin builder - attaching screenshots to illustrate. I assume that adding more posts will cause the same issue as with pages until I can finally post nothing! FYI I have been using Yoast Duplicate Post which may/may not have something to do with it.
Appreciate any help, thanks