NTB behaving badly in Chrome

I updated twelve systems today from NIS v20 to NIS v21.  On all twelve, the NTB in Chrome overlays the top portion of whichever website happens to be set at the browser start page ...

 

Fault-2.jpg

 

Once the page is navigated away from and returned to, the overlayed region is relocated into view...

 

Default-3.jpg

 

Exiting and restarting Chrome causes the issue to reoccur.

 

Kind regards,

John