Notification Settings area returns blank screen

Hello, I tried Activity Log and it seems to work except for when I click on the Notification Settings tab. When I do that, it hangs and then returns a blank white screen. When I inspect the page it’s just empty head and body. I tried disabling all plugins, still the same thing. I tried deleting and reinstalling the plugin, and resetting the Activity Log database, same result. Any ideas what it could be? Using PHP 5.6. Thanks!