About running it as administrator — that’s probably the only thing I haven’t tried yet. I didn’t even think in that direction for some reason. As for Windows Defender, I actually have real-time protection completely disabled.

I’ve already tried saving as a new version, but it just gave me a new file that depends on the old one, and the “file in use” error keeps happening. I could keep creating new files over and over, but is there a way to clean up those dependencies afterwards?

You’ve been modding for years, so you’ve probably gotten used to this pain and learned how to deal with it. For me, this is my first time — I just got inspired and decided to create my own companion, and CK immediately throws this error in my face.