KB4501375 fixed this for me.

I can see the custom views I had created once again.

Not sure if this is a Windows or Norton issue, so I started a thread on the Norton board and didn't have any more luck....

It's back ... rebooted today and the Defender setting window won't stay open. It opens fine for a few minutes after rebooting, but then I get a message in Action Center that says Windows firewall is...

A day later and all is still good! Thanks for your help!

Thanks Hydrate! Followed Step 3 of Option 2 and rebooted ... problem solved!

I'll keep an eye on it for the next couple of days and if all stays good, I will mark this thread closed.

Windows Firewall service is running and set to automatic.

Good Security and Maintenance Settings:
http://i68.tinypic.com/2r75ysg.jpg

Bad Security and Maintenance Settings:
http://i65.tinypic.com/ws7fiq.jpg

Good Defender Settings:...

Removed Norton, got Defender working, Reinstalled Norton and still have the same problem.

I noticed a couple of differences between my computers. The Defender settings screens look different.
...

AFAIK I didn't alter any Defender settings.

After doing more research, I believe it might be Norton interfering with Defender. A setting probably got doinked somehow.

I have 3 Windows 10...

Rebooted into Safe mode with and without networking with the same result:
I can open Windows Settings, but when I click on Update & security, the window disappears. So in Safe Mode, I can't even...

Screenshot attached. No problems found.

I noticed the problems post reset.

When I open Windows Defender Security Center, it opens and then closes itself.

I’m running Windows 10 Home, v1703, with the latest updates.

I run Norton Security as my primary AV & firewall...