here was my problem and how I fixed it
In my case, kb3000850 and 8 other updates were continually being installed and reverted.
second point, stating kb3000850 is optional was not the case for me, it was listed as critical.
For those reasons I did not hide the update.
I read through many other posts related to kb3000850 and found that in some cases having Avast av possibly contributed to the failure(s).
I disabled the three Avast shields, activated Windows Defender. (I did not remove Avast).
I restarted the computer, the updates reinstalled and reverted again. I shutdown the computer again and on this restart all 9 updates installed.
I will leave Avast disabled until several more windows updates apply correctly and then decide whether I'm safe enough with Defender.
Good luck to others who persist in getting beyond this nightmare