Thanks for the reply Eric.
I tried your suggestion but unfortunately don't get an error.
The upload location is present on the live server and permissions have been set.
Strangely, it doesn't seem to be affecting uploads, but when I do upload an image it is only displayed as a hyperlink (another screenshot attached) and none of the other functions of the file manager are there.
As I said I've used this a number of times with no problems - I think this must be server-related, but I can't think what?
Any more suggestions would be appreciated.