Cannot debug UWP app on Simulator: foreground can not be acquired

With Visual Studio for Windows, if I debug my Xamarin.Forms UWP app in "Local Machine" it works fine, but if I choose "Simulator", I get the following error when launching the debug session:

Unable to activate Windows Store app '10509MyNameAndSurname.myappname_6k78edmmrpdam!App'. The activation request failed with error 'Activate Application failed as foreground can not be acquired in Windows Simulator'. See help for advice on troubleshooting the issue.

If I click Help, it sends me to this page, which doesn't really mention my problem above. Any way to fix this? The main reason I want to know if it runs this way is because I'm getting a lot of "Cannot launch App" errors from the Windows App Certification Kit.

I restarted the OS and tried with a Blank App (C#, UWP): and got a different error:

Then I retried debugging my app, and got yet a new error:

Error DEP0700: Registration of the app failed. [0x80073CF6] An internal error occurred with error 0x80073D05. See http://go.microsoft.com/fwlink/?LinkId=235160 for help diagnosing app deployment issues.