Changing Font, preview of font not showing

Hi all

Untill a few weeks ago, when ever i changed text font style, I would see a preview of  the resulting text/font  showing as you click through font styles.

All of a sudden this is no longer happening.

So if you have a line of text, you are not able to get a preview of how it will look until you make the change (of font) selection, why has the preview function stopped?

Thanks

Ted