System Restore Max Usage Slider Being Reset By Some Ghost! (not Me)

I forced the anniversary update on both systems, HERE. No way of knowing what checks WU has made but nothing has been installed since on either system, one 30 hour ago and intensively used for several hours, the second just four hours ago. Both have now been manually reset to SR on, as they were before the update.

 

I have AU blocked per Woody Leonhard's instructions.
With no AU, and with no Acronis backups, "max slider" stays where I left it.
(Now 2% for C and D drives, both 1 TB)