I testing updating from 6914 to 7036 on Windows 10 1809 (17763.1098). The same is happening here. Updating without KillSwitch installed works and updating with KillSwitch installed does not work. I used a recently renewed version of my Proactive Security settings.
Because there is an issue with installing KillSwithc I “installed” it as described in:
These tests corroborate further that having KillSwithch installed prior to updating to 7036 breaks the update process.