Shortly after installing a recent patch for DF on Sep 7 the sleep mode on Win 10 stopped working. Disabling the DF management of the Screen Saver re-enabled sleep mode. Currently using the Photos option for screen saver which is inferior to DF. Win 10 is up to date. Any ideas?

Trying to answer your question about the DF hotkey I have been getting inconsistent results, so being explicit with parameters I have the following cases. The DF hot key is in Case 2.

Case 1:
a. Turn off all screen savers: lock screen saver, DF no screen saver, DF hot key: none.
b. Sleep mode works

Case 2:
a. Turn off all as in Case 1.
b. DF hot key to Start Screen Saver (ctrl+alt+9)
c. Press hot key, get blank screen followed by lock screen (no screen saver)
d. But, shortcut to DFSSaver.exe works; sleep mode works from windows Power Button icon.

Case 3:
a. Lock screen saver: Photo
b. Sleep mode does work from Power Button
c. Sleep mode works from ctl+alt+delete screen ONLY IF lock first.

I find this a bit confusing. Seems there is a problem with "automatically" invoking a screen saver. If turn off all screen saver options, the DFSSaver.exe works and so does Sleep Mode. But then can't have screen saver come up after idle time.

Probably nothing to do with DF but something to do with Windows. Or maybe I just have something screwed up.

If you can understand this, any further thoughts would be appreciated.

Thank you for your interest. After a period of abnormality things seem to be back to normal. The last thing I did was to run Windows troubleshooter. It reported the Power & Sleep settings Screen and Sleep were too long (120 minutes) and it set them back to 10 minutes. Things then worked: sleep mode, lock screen behavior, DisplayFusion, etc. 10 minutes is way too short, so I started incrental increases and now it is back to 120 minutes. Doesn't make sense to me. But then an awful lot of things don't make sense. This whole situation was an enormous expenditure of time for me. Again, thank you for your interest.