[1.1.100] Updating will not work

[Kyralessa]

Now mind you, I'm not saying it absolutely is your AV, but this certainly has the hall marks of it with your description of the zip file missing.

There's nothing in Windows Defender to indicate that it's quarantined that file, nor do I see any clear indication of why that file would've been quarantined. Furthermore, Factorio itself works, and installing a new version over the old one works; it's only the self-updating process that's broken.

I'm hoping to hear from one of the devs about this.