As I search for solutions to this problem, I notice that there are many references to similar problems on Windows 8/7. Although I upgraded to 10 from 8.1, I never had the screensaver problem before the upgrade.
I'm not really comfortable with just run this and it'll work approach. I like detailed explanations of what's wrong and how the fix works. I'm trying the "Console lock display off timeout" setting first.
Here's the setting from the article:
I found that the Attributes key already existed on my system, but it was set to '1' by default. I changed the value to '2' as would've happened if I had imported the registry file. I'm hoping it'll work.
Microsoft sure doesn't make it easy to get there...
Settings > System > Power & sleep > Additional power settings (completely different UI here > Change plan settings > Change advanced power settings > Display
The Console lock display off timeout setting didn't appear after I made the change. I don't think it'll fix the screensaver, but I'll wait before I change it back.
Update 20150812_201721-0500: Yesterday, it seemed that my screensaver was working, but I wasn't sure that it was because of the changes I made to the registry. When I go into the screen saver settings and save them again, it often starts working. So, I was going to wait a day and see if the screen saver kicked in during a normal day, but an update was automatically applied this morning (KB3081436) that has apparently reverted my change. I'll make the change again and see what happens.
What the heck is up with those registry keys?! Couldn't they have created a key named ShowConsoleLockDisplayOffTimeout instead of those long strings of hex characters?! </rant>
There is an updated video driver available for my system (HP laptop, Intel 4600 graphics), but when I install it performance is negatively impacted and whenever I run any games I get an error message that says access was denied to the graphics hardware. I had to rollback the driver update and use PowerShell to prevent the system from automatically re-applying it (ref: touchpad - Prevent Windows 10 from installing/updating a specific driver? - Super User). I don't know if the video driver update would've fixed the screensaver problem, but that's an unrelated issue.