however, the footer does not refresh to include the 'of 11' string. I have tried to refresh by closing the file and re-opening without success. Only new slides have the 'of 11' string. Any suggestions are appreciated as to how to prompt the old slides to refresh per the 'master' slide.
A quick and dirty solution would be to edit the slide master as follows: Resize the text field containing the slide number so it is small enough that you can add an additional text field in the freed up space and enter „of 11“ into it. If you align it properly, it should look like one string.