My Roku Express used to display the time in the upper left corner but since the 11.5 update the time is no longer displayed, although the clock settings still exist.
Is anything displayed there like "Not connected"? Have you restarted your Express from Settings->System (or Settings->System->Power)?
Resetting has not helped. When a channel is highlighted all that is displayed is, "* for Options", otherwise nothing is displayed where the time used to be.
That's odd. @RokuDanny-R may want to collect more information.
Are you sure it's in the upper-left? Mine is in the upper-right.
Also, make certain your TV didn't get put in some zoom mode that may be cutting off the edges.
Also, are you using a stock theme/wallpaper, or something else? If not stock, try switching to that and see if it reappears. It's possible some 3rd party wallpapers may not work properly with 11.5.