In the end I contacted Microsoft and allowed access. To cut a long story short there is a new major update in progress (KB4476976) My PC's were on Windows 10 (os Build 17763.253). After we installed the new version : Build 17763.292, it all works OK. Here is a link:
This is a major update and creates a windows.old folder. Make sure you have enough spare HD space (windows.old is 4.4 Gig)
Maybe those who had no problems had this update already - if so don't forget to reset restore points.
On my slow internet the whole thing took a long time. I leave it to those here to decide whether to get on with it now or wait for MS. It was dates 22Jan so maybe is being rolled out. Surprised DR Google did not mention it!!