It seems you have to be working with a long document to experience this anomaly.
Pages will do that with lengthy documents. I suggest you copy and paste parts of your document into a number of separate documents. Save them in a new folder. Think of these documents as 'chapters' of a 'book'.
I had not realised this problem was so common. Since my original post and having read the experience and suggestions of others, I have discovered one possible solution:
In the Save As window, tick the ‘Save copy as Word document’ box.
Open this new .doc file in Pages. All the bells and whistles that operate Pages are functional and the missing cursor problem disappears.
This so far has worked for me, although my document contains text only with basic formatting.
I suppose when your long doc is complete you can save it again back to Pages.
As a postscript I think it's high time Apple did something about this!
"All the bells and whistles that operate Pages are functional and the missing cursor problem disappears."
Only the bells and whistles that are also supported in MS Word will survive the translation to and from the Word file format. Apparently your document doesn't contain any features that are not cross-platform/application compatible.
"I suppose when your long doc is complete you can save it again back to Pages."
If you have edited your document in Pages, it is a Pages document. When you save it, it will be a Pags file, unless you choose to save it in MS Word format.
"As a postscript I think it's high time Apple did something about this!"