VS 2017 : The security debugging option is set but it requires the Visual Studio hosting process which is unavailable

This solved my issue:

Most likely, you have accidentally gotten the bit flipped to debug
with ClickOnce security settings. Can you get the project properties
for your app, go to the “Security” tab, and make sure to uncheck
“Enable ClickOnce Security settings” or check the “This is a full
trust application” radio button.