Brian, in my attempt to clarify my answer to your question I may have confused the issue even more. You asked “do you have the switch on under control panel, data logger?” I immediately checked this switch and it was on, and had been since updating in September.
Yesterday morning, before I left for a few hours, I unchecked the “Clear data when finished” box on the main screen during the startup, then shut down WD and the computer using “Save and exit” command, as usual. When I restarted yesterday afternoon, data for the period it was down was missing.
I left the “Clear data when finished” box unchecked when I again shut down last night. This morning on startup the overnight data was present normally for the first time since December 7th. Windows 10 was updated – again – last night, at least the second time since this problem started and maybe the third this month. Maybe this has been a Windows problem all along, and now I see the machine telling me there’s yet another update awaiting a restart. I guess we’ll see what happens this time.
Bruce